I had a weird issue similar to this with my 770 on my home network. The 770 would connect to the access point and be able to reach the internet fine, but none of the machines on my network could see or even ping the 770, and the 770 couldn't get to anything that was on the pcs on the network. The 770 showed up on my modem's list of connections though. It was very strange, and to be honest I don't know what I did to fix it.