TP-Link TL-WR850N v2

ModelVersionSoCCPU MHzFlash MBRAM MBWLAN HardwareWLAN2.4WLAN5.0100M portsGbit portsModemUSB
TL-WR850Nv2MediaTek MT7628NN575864MediaTek MT7628NNb/g/n-5---

Using the integrated tftp capability of the router.

First, enter failsafe mode:

Remove the power plug from the router.
Press and hold the WPS/RESET button.
Insert the power plug without releasing the RESET button, wait a moment for the USB LED to begin to blink.
Release the RESET button

No LED (maybe for attached ethernet ports) should be lit.

The device now uses the IP 192.168.0.2. It repeatedly tries to download a file named: tp_recovery.bin from a tftpd server with the IP 192.168.0.66.

The following steps will serve an openwrt firmware image to the device:

Download an appropriate firmware file from TP-LINK site.
You might need a “stripped” firmware version (without “boot” in the name). See bottom of this page for details and a download link.
Rename the file, so it matches the name required by the router: tp_recovery.bin

Configure your PC lan adapter ip address to IP 192.168.0.66 and connect your computer to one of the LAN ports of the router.

If you're using a linux distro you can run the following script

#!/bin/bash
USER=$(whoami)
sudo /sbin/ip addr replace 192.168.0.66/24 dev eno1
sudo /sbin/ip link set dev eno1 up
sudo /usr/sbin/dnsmasq --user=${USER} --no-daemon --listen-address 192.168.0.66 --bind-interfaces -p0 -K --dhcp-authoritative --dhcp-range=192.168.0.1,192.168.0.2 --bootp-dynamic --dhcp-boot=tp_recovery.bin --log-dhcp --enable-tftp --tftp-root=/home/xubuntu/Desktop/

Install a tftp server, for windows you can download one from http://tftpd32.jounin.net/

Run the tftp server and browse for the directory that contains the above firmware image. If necesary allow the connection of the server through your PCs firewall, once configured, shutdown the tftp server program, you will launch it again later.

If you connect your pc directly to a lan port on the router, be sure to put the router into failsafe mode FIRST (press reset button and plug power cable release reset button after 3 second), and then launch the tftp server, otherwise it might have problems trying to bind to the PC network interface.

Right after you launch the tftp server, a couple of blank messages will appear into the log window of the tftp server, this is normal, the third or fourth message will indicate that the process of file transfer is in progress.

After some time you will see all LEDs flashing once followed by a normal restart of the router

Now you can install the openwrt factory image of your liking, via the vendor firmware upgrade web page of the router.

You could try to flash directly using this method, an openwrt factory image (for this model obviously) to the router, for me it did not work, maybe you have better luck.

Using the integrated tftp capability of the router.

  1. Turn off the router.
  2. Connect pc to one of the router LAN ports.
  3. Set your PC IPv4 address to 192.168.0.66/24.
  4. Run any TFTP server on the PC.
  5. Put the recovery firmware on the root directory of TFTP server and name the file tp_recovery.bin
  6. Start the router by pressing power button while holding the WPS/Reset button (or both WPS/Reset and WIFI buttons)
  7. Router connects to your PC with IPv4 address 192.168.0.2, downloads the firmware, installs it and reboots. LEDs are flashing. Now you have OpenWrt installed.
  8. Change your IPv4 PC address to something in 192.168.1.0/24 network or use DHCP to get an address from your OpenWrt router.
  9. Done! You can login to your router via ssh.

Warning!
This section describes actions that might damage your device or firmware. Proceed with care!

With the TL-WR850N router, there is a catch: the stock firmware is obtained from the OEM: https://www.tp-link.com/ru/support/download/tl-wr850n/

  • in case the file name of this firmware file does not contain the word “boot” in it, you can simply revert back to original firmware
  • in case the file name of this firmware file does contain the word “boot” in it, you need to cut off parts of the image file before flashing it:

The following method applies for the V1, V2 and V3 since the bootloader is the same size.

An example of an image file with the word “boot” in it is TL-WR850N(RU)v2_3.16.0_0.9.1_up_boot(180808)_2018-08-09_11.26.41.bin.

Cut the first 0x20200 (that is 131,584 = 257*512) Bytes from original firmware:

dd if=orig.bin of=tplink.bin skip=257 bs=512

You should transfer the firmeware image to the /tmp folder and revert back to original firmware (if availlable you can flash the firmware via the webinterface as well):

Via the safer method using sysupgrade:

sysupgrade /tmp/tplink.bin

Or you use the mtd method:

mtd -r write /tmp/tplink.bin firmware

It is also possible to revert to the stock firmware using the method with tftp described in “recovery”. (you still need the firmware image without the boot part).

Model TL-WR850N
Version v2
Architecture: MIPS 24KEc
Manufacturer: MediaTek
Bootloader: U-Boot
System-On-Chip: MediaTek MT7628NN
CPU Speed: 575/580 MHz
Flash chip: SPI GD25Q64CSIG
Flash size: 8 MiB
RAM chip: ESMT M14D5121632A-2.5B
RAM size: 64 MiB
Wireless MediaTek MT7628NN
Antenae(s) 2 non-removable
Ethernet: 4 LAN, 1 WAN 10/100
USB: No
Serial: Yes
chassis port internal-port
WAN (blue) Switch eth0.2; Port X
1 (yellow) Switch eth0.1; Port X
2 (yellow) Switch eth0.1; Port x
3 (yellow) Switch eth0.1; Port x
4 (yellow) Switch eth0.1; Port x
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  • Last modified: 2021/05/02 12:53
  • by tmomas