I tried upgrading my mom's PC to Windows 8.1 and it wen't smooth for the most part except I could not connect to the wireless network anymore. The driver for the wireless adapter was installed (tried both microsoft's and TP-Link's) and networks were appearing, it just wouldn't connect. Took me awhile to figure out it wasn't connecting to the wireless n network, but would connect to g or b standard networks. The wifi adapter is supposed to be compatible with Windows 8 so I'm not sure why after the upgrade I'm unable to connect to the n standard network.
Wireless Adapter: TP-LINK TL-WN951N Wireless N300 Advanced PCI Adapter
Wireless Router: TP-LINK TL-WR941ND Wireless N300 Home Router
Router Firmware: DD-WRT v24-sp2 (03/25/13) std - build 21061