When I had ATT Uverse which had to use their router, EVERY time I tried to connect a new wifi device to the network the device would connect to the wifi but never connect to internet. Every time I had to unplug the router power, wait a minute, then plug it back in. Your situation may be something completely different, but if you have not tried it, it is worth a shot. Also, and I know people are ALWAYS recommending this, see if there is a firmware update for your router. Sometimes new firmware really does work.