Please consult →Installing OpenWrt (generic) and additionally read on here for WNDR3700 specifics.

To install simply use the stock WNDR3700 GUI to upload and install OpenWrt. Remember to use a factory.img image. Non North American users will get an warning regarding that OpenWrt identifies itself an NA, don't worry. You can just simple ignore this. Netgear WNDR3700 - OpenWrt New User(s)

Hold the 'System Restore' button on the underside of the router while powering it on, and hold the button until the power led blinks green. Then, upload the .img firmware as described in Installing OpenWrt via TFTP (see the section titled Bootloader contains TFTP server). However, note that the router will not accept the firmware when the filename is too long! Using firmware.img as filename should work. After upload, the power led is turned off and flashing starts, after that is finished the router will restart and the power led will eventually become stable green (it will be stable orange for quite some time first).

• Connect via serial console (also accounts for USB Serial Console)
• Interrupt U-Boot by pressing any key
• You may need to enable writes to the flash by issuing “protect off all”
• At the U-Boot promt enter the fsload command
• A TFTP server starts listening on port 192.168.1.1
• Start TFTPing the image now
  • For the V1: openwrt-ar71xx-generic-wndr3700-squashfs-factory.img
  • For the V2: openwrt-ar71xx-generic-wndr3700v2-squashfs-factory.img

tftp 192.168.1.1
mode binary
put openwrt-ar71xx-generic-wndr3700XXX-squashfs-factory.img
quit

Since commit 2fdd02cc, a factory image for WNDR3700v5 is available as snapshot. It can be flashed using nmrpflash. You can also debrick your router this way, as long as the bootloader is intact.

1. Connect your computer to a LAN port of the router
2. Set up an IP address within 192.168.1.0/24 on your computer (others work also if you adjust the following command)
3. Run the nmrpflash command as root (replace eth0 with the actual name of your network interface, IP address needs to be different from the one of your computer):

   # nmrpflash -i eth0 -f openwrt-ramips-mt7621-wndr3700v5-squashfs-factory.img -a 192.168.1.1

4. Power on or restart the router
5. Wait until nmrpflash tells you to reboot the router

See generic.sysupgrade.

See checks_and_troubleshooting.

Besides generic OpenWrt firmware distribution, there are customized builds based on it and managed by individuals in the community.

Announcements and updates can be found on the OpenWrt users forum.

Typically, these builds are intended to extend functionality and/or to improve performance of the firmware, as well as provide the end-user with a preconfigured setup.

Warning: As custom builds are mostly based on the trunk (bleeding edge) branch, they are much more prone to bugs and regressions.

In order to address this, some members also release builds based on the stable branch, thus reducing the potential of regressions, yet providing the advantages of customization (check out the link to hnyman's build below).

Specifically for WNDR3700, these are the longer maintained and the more frequently updated builds (as of July 2015):

• IPv6 oriented Openwrt build for WNDR3700 (managed by hnyman; trunk and stable builds)
• OpenWrt builds (BB) fully featured for various routers (managed by mk13139; trunk and stable builds)
• Optimized and feature rich trunk build for select routers (managed by arokh; trunk-only builds)

→flash.layout

The default network configuration is:

There seems to be an issue with the internal switch. I've observed this with all kinds of laptops and OS's on a dozen access points. The problem is that sometimes traffic with a destination of a wifi client will no longer be routed to it, leading to a non-working wifi client. My advice would be to uncheck 'learning and aging' under Network → Switch in LUCI, although this effectively may turn your switch into a hub. See https://dev.openwrt.org/ticket/13612

Numbers 0-3 are Ports 4 to 1 as labeled on the unit, 5 is the internal connection to the router itself. Don't be fooled: Port 1 on the unit is number 3 when configuring VLANs. vlan0 = eth0.0, vlan1 = eth0.1 and so on.

WAN port is a gigabit port. VLANs can be configured to work on both LAN and WAN.

To create a VLANx on WAN port (eth1) declare an interface as “eth1.x”. It can be further bridged with one of the switch ports if necessary.

For the LAN interface two actions are needed:

• Declare “eth0.x” interface
• Define switch_vlan configuration for each of the switch ports.

When vlans are defined on the switch ports VLAN0 cannot be used on eth0 any more. So the default router configuration must be changed, otherwise traffic stops on the switch ports and hard reset is needed.

Here is an example. WAN port is trunked on VLAN6 and VLAN4. VLAN6 has dhcp protocol defined. VLAN4 is bridged with one of the switch ports. LAN ports 1-3 are assigned to default VLAN1 (VLAN0 is not possible for some reason). LAN port 4 is assigned to VLAN4 and bridged with WAN.

So all the traffic that goes to switch port 4 will also pass to WAN's vlan4. Switch port numbering is other way around from physical ports.

config interface lan
	option ifname	eth0.1
	option type	bridge
	option proto	static
	option ipaddr	192.168.1.1
	option netmask	255.255.255.0

config interface wan
	option ifname	eth1.6
	option proto	dhcp
	
config interface vlan4
	option type 	bridge
	option ifname	"eth0.4 eth1.4"
	option proto	static
	option ipaddr	192.168.20.1
	option netmask	255.255.255.0
	option defaultroute 0

config switch
	option name	rtl8366s
	option reset	1
	option enable_vlan 1
	option blinkrate 2

config switch_vlan
	option device	rtl8366s
	option vlan 	0
	option ports	"5*"

config switch_vlan
	option device	rtl8366s
	option vlan 	1
	option ports	"1 2 3 5t"

config switch_vlan
	option device	rtl8366s
	option vlan 	4
	option ports	"0 5t"

Note: The VLAN switch configuration in Attitude Adjustment 12.09 has a bug ( https://dev.openwrt.org/ticket/7795 ), so that you need to first disable VLAN trunk and than reenable it like this:

# swconfig dev rtl8366s vlan 1 set ports '0 1 2 3t 5'
# swconfig dev rtl8366s vlan 1 set ports '0 1 2 3t 5t'

Note: The switch ports are not properly shown in the Backfire 10.03.1-rc4 Luci-interface, unless you add the chip name to the 'config switch' line: like 'config switch rtl8366s'. After making that addition, Luci shows the VLANs properly at the Network/Switch page. (Reference: https://dev.openwrt.org/ticket/7830 )

The switch on wndr3700 supports following led groups:

• Group 1: green leds for all ports on the switch
• Group 2: orange leds for all ports on the switch

Each group can be configured into one of 16 different modes:

• Mode 0: LED off
• Mode 1: Collision, Full duplex Indicator. Blinks when collision happens. Led is on for full duplex, and off for half duplex mode.
• Mode 2: Link, Activity Indicator. On for link established. Link/Act Blinks when the corresponding port is transmitting or receiving.
• Mode 3: 1000Mb/s Speed Indicator. On for 1000Mb/s.
• Mode 4: 100Mb/s Speed Indicator. On for 100Mb/s.
• Mode 5: 10Mb/s Speed Indicator. On for 10Mb/s.
• Mode 6: 1000Mb/s Speed/Activity Indicator. On for 1000Mb/s. Blinks when the corresponding port is transmitting or receiving.
• Mode 7: 100Mb/s Speed/Activity Indicator. On for 100Mb/s. Blinks when the corresponding port is transmitting or receiving.
• Mode 8: 10Mb/s Speed/Activity Indicator. On for 10Mb/s. Blinks when the corresponding port is transmitting or receiving.
• Mode 9: 10/100Mb/s Speed/Activity Indicator. On for 10/100Mb/s. Blinks when the corresponding port is transmitting or receiving.
• Mode 10: Fiber link Indicator. On for Fiber.
• Mode 11: Fault Indicator. On for Fault.
• Mode 12: Link, Activity Indicator. On for link established. Link/Rx Blinks when the corresponding port is transmitting.
• Mode 13: Link, Activity Indicator. On for link established. Link/Tx Blinks when the corresponding port is receiving.
• Mode 14: Link on Master Indicator. On for link Master established.
• Mode 15: LED value is read from a separate register

A sample configuration is orange LEDs for 10/100 Mb/s connections and green for 1000 Mb/s which are blinking on activity.

swconfig dev rtl8366s port 1 set led 6
swconfig dev rtl8366s port 2 set led 9

(Notice how swconfig port number is actually the led group number and last number is the desired mode)

You can also control blinkrate of the leds with values: 0 = 43ms, 1 = 84ms, 2 = 120ms, 3 = 170ms, 4 = 340ms, 5 = 670ms.

swconfig dev rtl8366s set blinkrate 2

Note: The default LED config built into Backfire 10.03.1-rc4 (and earlier) does not match the explanation printed on the router's bottom. To make the LED behaviour match the printed explanation (green LED for 1000Mb/s), use mode 6 for port 1, mode 9 for port 2 and mode 2 for port 5. This has later been patched to trunk (bleeding edge) and Backfire branch. You can either use the swconfig command or directly edit the file '/etc/config/network'. Reference: https://dev.openwrt.org/ticket/8103

Put below in rc.local

for i in /sys/class/leds/* ; do echo 0 > "$i"/brightness; done
for i in 0 1 2 3 4; do swconfig dev switch0 port $i set led 0; done

Install the package 'kmod-leds-wndr3700-usb'.

Add a USB LED configuration entry to /etc/config/system (you can edit the file manually or use Luci/System/LED_Configuration page)

config 'led'
	option 'name' 'USB LED'
	option 'sysfs' 'wndr3700:green:usb'
	option 'default' '0'

But that still just adds a default state to the LED. The LED will not yet turn itself on. You need to create an entry for the hotplug config:

You should add an entry to '/etc/hotplug.d/usb/10-usb' and your USB LED should be working. It won't do anything fancy (like blinking when there is disk activity), but it will turn on when a USB disk is connected and turn off when the device is removed.

Code for the file /etc/hotplug.d/usb/10-usb :

#!/bin/sh
# Copyright (C) 2009 OpenWrt.org
case "$ACTION" in
    add)
        # update LEDs
        echo "255" >/sys/devices/platform/wndr3700-led-usb/leds/wndr3700:green:usb/brightness
        ;;
    remove)
        # update LEDs
        echo "0" >/sys/devices/platform/wndr3700-led-usb/leds/wndr3700:green:usb/brightness
        ;;
esac

The LED should now react to inserting/removing USB devices.

Note: Reference to original info: https://forum.openwrt.org/viewtopic.php?pid=105502#p105502

→hardware.button

WNDR3700 buttons have currently (r25360) different names in Backfire and in trunk :

The button automatics is done with the wifitoggle package. It only requires hotplugging the button event to the '/sbin/wifi' script.

• The button toggles WiFi off, it at least one radio was on.
• And if both radios were off, it toggles WiFi on according to the specs set in normal wireless config.

To install the wifitoggle package and configure it just follow the steps below:

opkg update
opkg install wifitoggle

uci set wifitoggle.@wifitoggle[0].button=BTN_2
uci set wifitoggle.@wifitoggle[0].timer=0
uci commit wifitoggle

There is support for the WPS button removing the wpad-mini package and installing the full version of wpad & hostapd-utils packages.

Here is a central openwrt wps howto: https://wiki.openwrt.org/doc/uci/wireless#wps_options

If you have a WPS enabled network device (like a modern USB dongle), you can negotiate joining the routers wireless network without manually entering SSID & passkey. You just initiate “WPS authentication” by pushing the similar WPS button on the device (or launching the process by its driver/control software). After the device has initiated the authentication process, you can accept the transaction by using the WPS button on WNDR3700. The connection should then get negotiated, and in most cases in future your PC should remember the received network settings from then on.

After finding the information and browsing the hostapd package sourcecode, the needed actions for enabling the WPS button are pretty simple:

1. Using WPS authentication in requires replacing the default wpad-mini package with wpad and hostapd-utils. The reason is that the tool “hostapd_cli” and some needed support functions are not included in 'wpad-mini'. WPS authentication itself is launched with a command:

   hostapd_cli -p /var/run/hostapd-phy0 wps_pbc

   It tells the running hostapd daemon to participate in ongoing WPS authentication sequence. It needs to be run separately for each radio (= each existing hostapd process).

2. And it only works if the '/etc/config/wireless' has been modified to include info about WPS authentication being allowed by adding the option 'wps_pushbutton' '1' to the wifi-iface section of (each) radio. (Looks like the version of hostapd scripts in OpenWrt does not support the full scope of hostapd's capabilities, so many of the config options documented in hostapd docs are left unused.)
3. That config file is read when radios are turned on, so after editing the config, restart the radios in WNDR3700. At this point, you should be able to test it by running it from command line.
   If the message gets passed to hostapd, you should see there result 'OK' there. Otherwise the result is 'FAIL'.

   root@OpenWrt:~# wifi
   [..]
   root@OpenWrt:~# hostapd_cli -p /var/run/hostapd-phy0 wps_pbc
   Selected interface 'wlan0'
   OK
   root@OpenWrt:~#

4. Add a hotplug button event script to launch the process. I modified directly the hostapd package source ( /package/hostapd/files/wps-hotplug.sh ), as the hotplug script gets automatically installed to /etc/hotplug.d/button/50-wps with the package. See below.
   The script launches hostapd_cli for each radio and lights the WPS led for 10 seconds. There is no monitoring of the result, or anything like that. It is just a dumb script using the hostapd_cli command to pass the message to the hostapd daemon.
   Note: button is called BTN_1 in Backfire, wps in trunk. /etc/hotplug.d/button/50-wps

   if [ "$ACTION" = "pressed" -a "$BUTTON" = "BTN_1" ]; then
           for dir in /var/run/hostapd-*; do
                   [ -d "$dir" ] || continue
                   logger "WPS button active: $dir"
                   hostapd_cli -p "$dir" wps_pbc
           done
   fi

   /etc/config/wireless

   config 'wifi-iface'
           option 'device' 'radio0'
           option 'network' 'lan'
           option 'mode' 'ap'
           option 'ssid' 'public'
           option 'encryption' 'psk2'
           option 'key' 'SecretKey'
           option 'wps_pushbutton' '1'

   If everything goes ok, you should see in Syslog not only the button events, but also succesful WPS authentication.

If you just want a straightforward simple reset button functionality, you can install the restorefactory package and configure it:

opkg update
opkg install restorefactory

Minimum configuration is to set the right value for the reset button. Reset button is 'reset' in trunk, 'BTN_0' in Backfire final.

uci set system.@restorefactory[0].button=reset
uci commit system

After you reset to the factory defaults you have to reinstall and reconfigure the restorefactory package. You can skip this step if you build your own image which contains a preconfigured restorefactory configuration.

Using a USB-serial adapter one can easily create a USB-serial console for this device. See router_with_usb_port for more on setting it up.

To connect to the console use your favorite terminal software - mine is miniterm and the default baud rate on my system was 9600: miniterm -b9600 -d/dev/ttyS0

Note: This will void your warranty!

• To remove the cover use a Torx (T-8) screwdriver.
• There are two screws easily visible on the bottom of the case.
• There are four more screws under the rubber feet. The feet are not glued to the plastic and can easily be removed and pushed back into place once reassembled. The feet have rubber tethers, but you can slide them out gently without damaging them, and later you can reinsert them just as easily. Don't forget to put them in a plastic baggie so you don't lose them!

Internal J1 4-pin connector

3.3V serial port voltage !!!

COM port settings: Speed:115200, Data bits:8, Stop bits:1, Parity:none, Flow control:none

Internal J3 connector

14 Pin header

See port.jtag for more JTAG details.

Onboard Voltage Regulator is a STMicroelectronics ST1S10 which is described by ST as a

3A, 900 kHz, monolithic synchronous step-down regulator IC

Full details of the onboard ST1S10 Voltage Regulator are here

http://www.st.com/stonline/stappl/st/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00169322.pdf

There are three total ST1S10 chips near the capacitors on the upper right of the board.

If you have a basic familiarity with RS232 signals and putting together basic electronic components, you should be able to follow these instructions to create a cable to attach to the WNDR3700's serial port.

The author of this section prefers a two-step process, that of using a USB-to-9-pin-serial (DB9) connector for the computer, and then building a separate 9-pin-serial-to-board interface. This allows you to leave the connector plugged into the board all of the time (and close the plastic case of the router!), without having a USB dongle hanging around when not using it. If you use a ribbon cable to connect to the header on the router, you can actually snake it out between the 4-port LAN jack and the WAN jack and still get the router's case back on (albeit a bit snugly), so the system looks pretty clean and polished even after adding the serial port connector.

For the computer-to-9-pin-serial part, you probably have two options:

1. Buy a Nokia CA-42 cable and be comfortable stripping wires and using a multimeter.
2. Buy a premade USB-to-DB9 RS232 serial cable. IMPORTANT NOTE I haven't bothered to look to see if the standard RS232 voltages are compatible with the WNDR3700 board. I think I recall reading somewhere that the CA-42 cable is 3.3V, and I don't recall offhand what RS232 calls for. If you buy a premade USB-to-DB9 RS232 cable, make sure to check the output levels with a voltmeter to ensure that you don't fry anything!

Never ever connect RS232 directly to your router board !!! The +/- 12V RS232 will be frying your board. You need a 3V-TTL to RS232 level shifter like MAX3223 in between.

For step 1:

If you buy a premade USB-to-DB9 RS232 cable, this step is already done. (Whichever method you use, make sure that your OS has drivers for the USB converter that you are planning to use!)

If you go the CA-42 cable route, follow the “Determining the wiring assignment of your cable” steps listed in this page: http://buffalo.nas-central.org/index.php/Use_a_Nokia_Serial_Cable_on_an_ARM9_Linkstation. This page refers to a different router product, but the CA-42 cable being used is the same and your goal is to determine the pin/color assignments. You have to chop off the fancy Nokia connector and then strip wires to test wire colors with your multimeter to figure out which color corresponds to which Nokia pin number. Once you've figured that out:

Pin 6 of the Nokia connector should be wired to pin 3 on the DB9. Pin 7 of the Nokia connector should be wired to pin 2 on the DB9. Pin 8 of the Nokia connector should be wired to pin 5 on the DB9.

You should wire this cable with a male DB9 connector, which will connect to the female connector that you put on the board side of things.

For step 2:

For connecting to the WNDR3700 itself, forum user whiskas previously posted the pinout of the connector at http://img387.imageshack.us/i/26102009417.jpg/. The four pins on the board (reading from left to right in whiskas's photo) correspond to DB9 pin numbers 5, 3, 2 and no connection. You'll probably want to buy a crimp-style socket (I used a “IDC 10-pin dual row socket”, which has more pins than we need but which works fine) and a ribbon cable that connects to it. Buy a 9-pin female DB9, carefully sort out which pins in the ribbon cable need to be connected to what, and crimp them into the right place. If you use crimp-style connectors, you can do this with no tools other than steady hands, and the IDC socket will slide right onto the board without having to solder anything.

If, for whatever reason, you would prefer to avoid tftp flashing, it's possible to load a new image with ymodem (loady) or kermit (loadb). It's a good idea to use iminfo to verify the image's checksum before copying it to flash with cp.b. Remember to use the sysupgrade .bin file even if this is your initial flash from the factory firmware; the extra header in the factory .img is NOT required when flashing from U-Boot.

ar7100> loady 80800000
## Ready for binary (ymodem) download to 0x80800000 at 115200 bps... 

(Begin the ymodem or kermit transfer)

## Total Size      = 0x004d0004 = 5046276 Bytes
ar7100> iminfo 80800000

## Checking Image at 80800000 ...
   Image Name:   MIPS OpenWrt Linux-3.3.8
   Created:      2012-07-01  17:49:09 UTC
   Image Type:   MIPS Linux Unknown Image (uncompressed)
   Data Size:    914224 Bytes = 892.8 kB
   Load Address: bf070000
   Entry Point:  bf070000
   Verifying Checksum ... OK
ar7100> erase 0xbf070000 +0x004d0004
Erase Flash from 0xbf070000 to 0xbf54ffff in Bank # 1 
First 0x7 last 0x54 sector size 0x10000
  84
Erased 78 sectors
ar7100> cp.b 0x80800000 0xbf070000 0x004d0004
Copy to Flash... write addr: bf070000
done
ar7100> boot

Note that the size value (0x004d0004 in this case) will vary from one image to another. Don't omit the “+” in the erase command as it's part of the command's syntax.

According to the release notes in the NETGEAR-supplied GPL firmware, U-Boot can be upgraded using the following procedure. Note that you do not need to update U-Boot in order to install OpenWrt. Additionally, this has not yet been tested by the author of this wiki page, and you can permanently brick your router (with little hope of recovery, other than possibly finding a JTAG interface) if your U-boot image becomes corrupted:

Please burn u-boot-wndr3700-dni6-V1.7.bin
Set up a tftp server on your PC, its ip address is 192.168.1.12.
Entering into boot loader
ag7100> set serverip 192.168.1.12
ag7100> tftp 0x80010000 u-boot-wndr3700-dni6-V1.7.bin
ag7100> erase 0xbf000000 +0x70000
ag7100> cp.b 0x80010000 0xbf000000 0x50000
ag7100> reset
Entering into boot loader again
ag7100>bootm
Then the device should be in tftp recovery mode. Please run the command
"tftp -i 192.168.1.1 put WNDR3700U-V1.0.4.49.img" on MS-DOS of your PC.

NEW: More and More people reports serious issues after correctly replace ram chips on WNDR3700V2. For now users are advised to stay away from extending RAM on WNDR 3700V2 untill we will have positive feedback on this procedure.

Warning: There are reports (User batu at http://eko.one.pl/forum/viewtopic.php?id=2454) that 333Mhz chips dont work with wndr3700v2. Use 400Mhz chips if available.

I used two Samsung K4H511638D-UCCC. You can use chips from other manufacturers, but they should be DDR400 32Mx16 organization in the package TSOP-II 66pin. Chips with other organizations, such as 64Mx8, do not fit.

A list of compatible chips:

U-Boot report after adding memory

''U-Boot 1.1.4DNI1.6 (May 22 2009 - 16:37:44)

WNDR3700U (ar7100) U-boot 0.0.12
DRAM:  b8050000: 0xc0140180
**128 MB**
Top of RAM usable for U-Boot at: 88000000
Reserving 315k for U-Boot at: 87fb0000
Reserving 192k for malloc() at: 87f80000
Reserving 44 Bytes for Board Info at: 87f7ffd4
Reserving 36 Bytes for Global Data at: 87f7ffb0
Reserving 128k for boot params() at: 87f5ffb0
Stack Pointer at: 87f5ff98
Now running in RAM - U-Boot at: 87fb0000
id read 0x100000ff
flash size 8MB, sector count = 128
Flash:  8 MB
In:    serial
Out:   serial
Err:   serial
Net:   ag7100_enet_initialize...
''

The procedure below covers hardware revision 1. Revision 2 only has U.FL connectors for the 5 GHz antennas (PJ2 and PJ4), while the 2.4 GHz connectors are replaced with dummy connectors (presumably a Hirose testing connectors used in production). So for revision 2 the PJ5 and PJ6 connectors will have to bypassed and the coax cable soldered directly to the PCB.

You will need:

• 4 cable U.FL-F (female) to RPSMA-F (female) app. 13 centimeters long
• 4 Antenna (preferably 2 2.4 GHz and 2 5 GHz antenna), e.g. Level One (OAN-0501).

On board removes:

1. Connectors (SWD) PJ2, PJ4, PJ5, PJ6
2. Switches AS6, AS8, AS9, AS10
3. Capacitors AC77, AC113, AC148, AC186

In place of the connector solder in U. FL connectors.
Solder shorts instead of capacitors AC77, AC113, AC148, AC186.
Solder shorts between 3 and 5-pin AS6 and AS8.
Solder shorts between 3 and 6 pin AS8 and AS10.

Drill four drill holes 6.5mm in the left side of the upper lid.
In a hole fasten cables UFL-F/RPSMA-F.
Insert the connector into the board as in the photo, and assemble the router.
Fasten to the connectors RPSMA-F antenna and turn on.

https://downloads.openwrt.org/chaos_calmer/15.05.1/ar71xx/nand/openwrt-15.05.1-ar71xx-nand-wndr3700v4-ubi-factory.img Then you probably would like to update to recent OpenWrt version. In 15.05.1 there are no known regulatory issues. If you find some, please fill up a bug.

While the WNDR3700 (and WNDR3800) are great routers, there have been a number of issues with them. Some have been recently fixed, others are still present. Note that most of these issues are related to the Atheros chipset and are not unique to the WNDR3700. Here's a short list of major issues:

• Wifi stopped working after a while (fixed in AA 12.09 in April 2013, https://dev.openwrt.org/ticket/11894)
• Problems with internal switch causing traffic to a particular wifi client to be ignored (workaround present, https://dev.openwrt.org/ticket/13612)
• Failed to stop TX DMA messages in syslog (in AA 12.09 and later these are likely harmless and can be ignored, https://dev.openwrt.org/ticket/11862)
• For more issues, you can search on tickets at http://dev.openwrt.org/ for “wndr3700” or the chipset (usually “ar71”)

Previous versions had major trouble with regards to stability in an office environment. Starting with AA 12.09 however, combined with the internal switch workaround mentioned above, these access points seem finally stable. I (Syzop) use around 20 of these on a high school which are used intensively with many associate/disassociate events.

If you happen to brick your router, do not fear. You can use TFTP file transfer to flash the router with a new firmware. Note that this TFTP recovery mode is separate from Openwrt's own “failsafe mode” and is offered by the original u-boot boot manager by Netgear, so it should be enabled with either an original Netgear firmware, a working Openwrt firmware or a bricked Openwrt firmware.

Note: WNDR3700 may also automatically enter the TFTP recovery mode, if you have flashed a bad firmware image. That is indicated by the power led blinking slowly and steadily, much slower that during a normal Openwrt boot.

For TFTP recovery you need:

• A TFTP client for your computer. There are both command-line tools and GUI versions available.
• Your computer must have an IP address from the 192.168.1.x network, as the router failsafe mode defaults to 192.168.1.1. You might need to manually config the address, as some operating systems change the IP to a link-local 196.254.x.x address after a while if there is no DHCP server.
• A new firmware to flash in. Either an original Netgear firmware or an Openwrt “factory.img” firmware. “Sysupgrade” version will not work.
• Access to router's reset button

Steps needed in the flashing process:

1. configure and connect PC
2. power on the router
3. press and hold the RESET button as soon as the switch LEDs light up.
4. keep holding RESET until the power LED begins to flash orange and then green.
5. once the power LED is flashing green, release RESET
6. start the TFTP transfer to router at 192.168.1.1.
7. wait a few minutes for the router to complete flash. It should reboot automatically.

Please note that the TFTP transfer is quick, as the file is stored in RAM. However, the flashing process itself will take several minutes, after which the router should reboot automatically. Be patient – it will eventually come up as a brand new factory-fresh router with NETGEAR firmware (or Openwrt if you used the Openwrt 'factory' firmware version for debricking). Original source: https://forum.openwrt.org/viewtopic.php?pid=103295#p103295

Alternative advice

Forum user ole.h previously posted a method for unbricking the router easily with a TFTP client. Further to his post, if you use the factory reset button method, you don't need to worry about building a serial cable, trying to tap into any crazy boot timing sequence, or do anything else particularly tricky. It is simple and the following step-by-step process (cribbed from the ole.h's earlier notes, as well as from http://cyberstorm.altervista.org/wag354g/guides/howto_unbricking_wag354g_en.txt) will get you going. This assumes that you have a copy of the stock NETGEAR firmware in the current directory.

1. Configure your ethernet connection (on the client machine you're using to configure the WNDR3700) using a static IP as 192.168.1.2, netmask 255.255.255.0. (The WNDR3700 in factory reset mode is going to come up as 192.168.1.1.)
2. Connect your computer to one of the LAN (not WAN) ports on the router.
3. Start a continuous ping from your client computer to 192.168.1.1 (Linux and Mac OS ping will continue until stopped by default; Windows ping by default sends 4 pings and then stops, so use “ping -t” under Windows); probably nothing will answer these pings yet, but you can use the output to tell you when the router is ready in the next couple steps.
4. Power the router off.
5. Hold down the factory reset button on the bottom of the case. Now turn the router back on while continuing to hold the factory reset button…
6. Wait until the router is listening on 192.168.1.1 (this takes 45-60 seconds; to confirm, you can ping 192.168.1.1, and see if it responds; it's best to start a sequence of ping requests above, before your hands get busy with the factory reset button).
7. Release the factory reset button. (If you happen to have a serial cable connected, you'll see that the system is in firmware recovery mode and that it will be waiting for you to upload firmware. But you don't need the serial cable at all.)
8. Run a tftp CLIENT on your computer (enter no hostname on the command line) and enter the following:

   verbose
   trace
   rexmt 1
   binary
   connect 192.168.1.1
   put WNDR3700-V1.0.4.35NA.img (or whatever the filename is that you are trying to flash)

Once done, the router will flash itself to the stock NETGEAR firmware file that you provided and reboot automatically.

Openwrt offers a generic failsafe mode, which can be launched during a few seconds early in the boot process. With WNDR3700 the correct moment is when the power LED changes from steady orange to blinking green. If you at that moment press any button (WPS, Wifi or reset) during the next two seconds, you enter the failsafe mode, in which you can access the console with telnet. Successful entrance to the failsafe mode is indicated by a rapidly blinking power LED.

WNDR3700 provides the failsafe waiting moment indication messages both to the serial console and to the network, just like described in the failsafe mode article.

• OEM source code and toolchain: Netgear KB Article 2649 - Netgear Open Source Code for Programmers - GPL

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