I have 6D and trying to pair it with my computer running Windows-8. It worked once, but after that pairing utility never finds the camera. The C:\Program Files (x86)\Canon\EOS Utility\WFTPairing\EOSUPNPSV.exe is taking around 40% of the CPU cycles, and stays there.

I reset the camera WiFi settings and now its in the last stage of pairing.

I see this on the camera:

EOS-C78751 pairing in progress. Start pairing software on computer.

On the computer WFTPairing is running, and as mentioned taking huge chunks of CPU. Firewall turned off on my computer. I checked with a UPnP spy utility, and can see 6D on the network, but the Pairing utility seems to not. I tried reinstalling EOS utility multiple times too.