TP-Link TL-WR850N v2

Using the integrated TFTP capability of the router:

• Turn off the router.
• Connect TFTP host to one of the router LAN ports.
• Set your TFTP host IPv4 address to 192.168.0.66/24.
• Run any TFTP server on the PC.
• Host the TFTP-recovery firmware TFTP server, and name it tp_recovery.bin.
• Start the router by pressing power button while holding the WPS/Reset button (or both WPS/Reset and WIFI buttons).
• Router connects to your TFTP host with IPv4 address 192.168.0.2, downloads the firmware, writes it, and reboots.
• LEDs are flashing, you now have OpenWRT running on the router.
• Change your TFTP host back to DHCP client.

Recovery is done the same way as installation.

→ generic.uninstall

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).

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