I recently upgraded my laptop to Windows 8.1 from Windows 8 after third party VPN software finally became available. Initially I got BSOD from Intel Wifi driver so upgraded them along with NVidia drivers.
Wifi worked at home but not when tethered to my phone – what’s going on? Troubleshooting revealed a DNS issue.
Turns out Hyper-V (installed as part of Windows Phone SDK) had bridged the Wifi network connection and forced the DNS server to be my home DNS (which explains why my home WiFi worked).
Under network connections: Right-click->Remove this connection from the bridge resolved the issue for me.