I think it might be of interest what I’ve answered in response to one of my commenters. So I decided to put in here as well:
Going back to stock firmware is not that complicated although it can’t be done from the web interface.
First you need to get a stock firmware from TP-Link. I suggest you don’t grab the latest one as it comes along with a new bootloader. The new bootloader is either having a bug or by design crippled but you will no more be able to use TFTP with that one. It’s broken. Take an older one, e.g. TL-WA801ND_V2_120524. Unzip and copy the firmware to the device:
scp -l root wa801nv2_en_3_13_20_up\(120524\).bin IP ADDRESS:/tmp/tplink.bin
Then you need to logon to it via ssh and flash the firmware:
cd /tmp mtd -r write tplink.bin firmware
It will reboot and come back again running the stock firmware.