I have seen this a few times.. especially with the OLD touchpad.
Which touchpad do you have? The SMC or the technicolor?
With the other router that is connected, are all 4 lights on? (power, a world, a wireless antenna, and an antenna with a lock?)
When i had the old SMC touchpad, often if there was a full drop for a while, it would not re-connect on its own. I would have to call into tech support, they would change a setting, force a reboot.. then it would come back on.