Does the iPad get a signal and join the network?
Try turning the router off for about two minutes. While it is off go into your Settings on the iPad, Wi-Fi, choose the network and tell it to forget it.
After the router is back up try connecting to the network again and see what happens.
If that does not work give your provider a call. Sometimes they limit the number of IP addresses a router will give out. If so you may need to get them to increase that number, or use an ethernet port out of the router to make your own network with yet another wireless router.
Good luck.