Problem with TFTP instalation - Archer A6 downloads file, but doesn't install it

I've been trying to install OpenWRT 19.07.4 on my Archer A6 v2 (EU). Unfortunately uploading firmware directly produces Invalid file type. so I've decided to use TFTP server. I set my laptop's IP address to, plugged it to my router's LAN port with a network switch inbetween. My router is pretty much Archer C6. In logs it even requested for ArcherC6v2_tp_recovery.bin. I plunked OpenWRT image and renamed it to that name. Restarted my router and put it in tftp recovery mode, by holding RESET button, until WPS Led lit up. The router succesfully requested for the file and my laptop kindly provided it. I saw a transfer icon and it went up to a 100%. In logs I could see that file transferred succesfully. However it didn't install. After a while my router just booted up with old firmware and settings. I tried it even with official TP-Link firmware, it downloaded, but didn't install.

Hello, I also bought this dev and trying to flash.
I try many firmware's, include first from tp-link, ver.1-1-0, via tftp and 100mb switch, and also without success.