Linksys WRT300n v1

This device is NOT RECOMMENDED for future use with OpenWrt due to low flash/ram.
DO NOT BUY DEVICES WITH 4MB FLASH / 32MB RAM if you intend to flash an up-to-date and secure OpenWrt version onto it! See 4/32 warning for details.

1) This device does not have sufficient resources (flash and/or RAM) to provide secure and reliable operation.
This means that even setting a password or changing simple network settings might not be possible any more, rendering the device effectively useless. See OpenWrt on 4/32 devices what you can do now.

2) OpenWrt support for this device has ended in 2022.
19.07.10 was the last official build for 4/32 devices.

802.11n “draft” MIMO router with 100 Mbit/s switches.

Version/Model Launch Date S/N OpenWrt Version Supported Model Specific Notes
v1 2006-07 CNP01 Trunk (r45293) -

Later versions (1.1, 2.0) are significantly different hardware, so for the purposes of OpenWRT consider v1 a distinct model.

CPU Ram Flash Network USB Serial JTag
Broadcom 4704@300MHz 32MiB 4MiB 4 + 1 No Yes Yes/3.02

Please check out the article flash.layout. It contains an example and a couple of explanations.

This section deals with how you install OpenWrt from a device freshly opened. Plus the steps required such as reset to factory defaults if the device has already been configured

Note: Reset router to factory defaults if it has been previously configured.

  • Update with OpenWRT .bin file
  • Wait for it to reboot
  • Telnet to and set a root password

This only seems to work when the firmware is corrupt (or the bootloader thinks it is). Bootloader has a TFTP server on

Hint: when ping shows a ttl=100, the bootloader is running, while ttl=64 means the firmware is running.


If you have already installed OpenWrt and like to reflash for e.g. upgrading to a new OpenWrt version you can upgrade using the mtd command line tool. It is important that you put the firmware image into the ramdisk (/tmp) before you start flashing.

Terminal Upgrade Process

  • Login as root via SSH on (or whatever you configured it to).
  • Use the following commands to upgrade:
cd /tmp/
sysupgrade /tmp/openwrt-brcm47xx-squashfs.trx

Basic configuration After flashing, proceed with this.

Numbers 0-3 are Ports 1-4 as labeled on the unit, number 4 is the Internet (WAN) 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.

Port Switch port
Internet (WAN) 4
LAN 1 3
LAN 2 2
LAN 3 1
LAN 4 0

hardware.button on howto use and configure the hardware button(s).

The Linksys WRT300n has two buttons. Here, we merely name the buttons, so we can use them in the above Howto:

BUTTON Location Event
Reset back reset
Reserved top ses
Architecture: MIPS
Vendor: Broadcom
bootloader: CFE v4
System-On-Chip: Broadcom 4704
CPU/Speed Broadcom BMIPS3300 V0.6 @300MHz
Flash-Chip: Intel JS28FR320 C3BD70 A5437913
Flash size: 4 MiB
RAM: 32 MiB
RAM-Chip: hynix 602U HY5DU281622ETP-J
Wireless: Broadcom BCM4321 2.4ghz 802.11bgn
Ethernet: Broadcom 4704
Ethernet Switch: Broadcom BCM5325
USB: No (maybe with some hw mods, BCM4704 supports it)
Serial: Yes

FCC Exhibits List

Model Number


FIXME Extract from FCC Exhibits


FIXME Extract from FCC Exhibits

Note: This will void your warranty!

  • To remove the cover do a/b/c

Each blue cover is held in place by 2 bracket-like clips in the front (LEDs side) and 2 round brackets in the rear (network ports side). To remove the top cover (the one with the button going through it), pull the back of the blue cover away from the router and towards the front (in such a manner that the front clips act as pivot). The round clips should release relatively easily. Then, gently shake the cover left and right until the angle bracket release from their sockets. To remove the bottom blue cover, you first need to pull the rubber feet towards you (there is a spring mechanism that will allow them to be pulled) enough so that you can rotate them 180 degrees. Once the feets are out of the way, proceed in the same manner as for the top cover.

Once the blue covers are out, you will need to unscrew 4 T10 secure Torx screws located in the corners under the bottom blue cover. After that, you will need to remove the black front part. In order to do so, you will need to squeeze all 4 pairs of arrow-like clips attaching it to the main (grey) cover. Using longnose pliers, gently squeeze one pair together and tilt the black part slightly such that the clips won't clip back again. Repeat for all 4 pairs of clips.

Main PCB

FIXME Extract from FCC Exhibits

According to simucas

  • Connector (JP2) is located behind the WAN (blue) port.
  • Pinout left to right): GND flow? RXD TXD VCC (assuming that the flow? is the flow-control pin from the router).
  • Needs a level-shifter (MAX232 or equiv) to connect to a standard serial port.
  • Settings: 115200 8-n-1

general information about the serial port, serial port cable, etc.

port.jtag general information about the JTAG port, JTAG cable, etc.

How to connect to the JTAG Port of this specific device:

Photo of PCB with markings

  1. you could read about bootloader in general
  1. as a beginner, you really should inform yourself about soldering in general and then obtain some practical experience!
  • b43legacy is limited to 54 Mbps with the BCM4306 radio.
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  • Last modified: 2021/04/18 06:59
  • by tmomas