Have you tried the driver for Windows 8 on 8.1? http://www.tp-link.com/en/support/download/?model=TL-WN722N&version=V1#tbl_a

Are you using the latest firmware? What's the working mode of WA901ND? Did you try to change a channel to see what happens?

I can see you post. :)

Have you tried different web browsers or different PCs? At the very beginning, does the web interface work normally? You may reset it to facotry defaults to test?

vladimir.sirma wrote Kinda sad, since official TP-Link support said: For your problem, maybe you can ask some suggestions from Microsoft support as they know windows server better. Sorry for that!...

Ryan, what kinds of client? Why not assign a static IP for the client directly?