I have been reading these issues going on. I am not real computer smart but I will try to tell you what I have learned. iPad 1 will not connect with the wifi. Have Cable One for a service provider. They say the Arris does not get along with every device. They have found it has an issue that devices having an 06 in their address are rejected by Arris Modem. The problem is one cannot see if 06 is in the physical address until after they buy the product and use it. Another iPad2 user hooked up to the Arris fine. I took the iPad1 to library and hooked up fine. Now they suggest the Arris is good for the phone part of the service and to use Motorola for the high speed data part. Not real happy with that solution. More money and splitting up the signal too.
The problem is more likely to be with the modem and not with the iPad. Have you tried resetting the modem?