@clos73 

From what I understand, the V1 TL-WPA4220 V1 with printed speed on the device AV500 will become technically speaking AV600 devices after you update the FW. Even the name in the webinterface is now changed to AV600 (from AV500) before. I did the same on my two TP-WPA4220 I recently bought. 

As long as you selected the correct V1 firmware for your TL-WPA4220, the device should still work. I did not try V2 or any newer firmware for my V1 devices.

I suggest to reset the TL-WPA4220 and try again to repair the Powerline, I have severe issues with my two TL-WPA4220 regarding WiFi but the Powerline function works all the time.