Make sure the system time on the router is correct. http://www.tp-link.com/en/faq-1740.html

Change the 5G channel on your router

Is the light on the adapter always on when it does that? What's your computer system? Try reinstall the driver, shut down the firewall or antivirus.

Looks like it's totally dead, no power at all

I think they released tpplc utility can help to turn off the powersaving mode now. http://www.tp-link.com/us/download/TL-WPA4220KIT.html#Utility ekandefer wrote MY WPA4220 has the same problem I have...

The plug can't be rotated. You may check the overview page: http://www.tp-link.com.au/products/details/cat-18_TL-PA9020P-KIT.html#overview