Why won't my iPad connect to the Internet if I'm more than five feet away from my router?

Maybe the internal antennae wire became disconnected.

Try the WiFi analyzer application. It will show you signal strength for each WiFi connection including others. It is a great app for identifying WiFi problems. Maybe there is an overlapping WiFi signal on the same channel. If that is so, just change the router's channel to one with less interference.

Or try other WiFi spots to test your antennae.

If it is having the problem with other routers, I would hope it is under warranty. But the antennae wire is usually easy to reattach, at least on Android pads I have repaired.

Maybe it's caused by weak WiFi signal. The longer you stay,the weaker signal will be. You can just try to strength your WiFi performance,like change WiFi channel,update your router and so on,http://www.mywifirouter.me/blog/7-tips-for-how-to-...