I don't know what I'm doing, but I had the same problem and accidently solved it. I went to settings-wifi and then touched the blue arrow button next to my network name. I then touched "forget this network". I then closed settings and opened safari. I got a message that I couldn't access the internet because I wasn't connected to a network. I removed this message and then waited. Eventually (within 30 seconds) a join network box appeared, I touched it, typed in my password, and it suddenly worked.
I'm having the same problems. My computers have no problem connecting, but my iPad intermittantly can't connect to the internet. I've tried "forgetting" the network, but it that won't fix it. The only thing that fixes it is rebooting my wireless router. But that is not an acceptable solution, I shouldn't have to keep doing that. Must be some conflict with the IP address, but can't figure it out.
I had this problem at work after resetting my Ipad 2 to deal with a different problem. I called Apple Support, which had nothing to add beyond what can be found in the threads and support articles here. When the Apple Support person started pushing me to reset my Ipad2 to factory settings, wiping out everything, I said forget that.
Here's what worked for me: 1) turn off my cellular data service 2) make sure none of my available wireless networks were "known" 3) turn on Safari and ignore/dismiss the message that Internet service wasn't available 4) when the message about available networks finally came up, pick the one I wanted and put in normal sign in.
And I'm up! Without returning to factory settings.
Help! I'm having the same problem. My laptop PC connects fine, but my iPad finds the network, shows a connection with strong signal, but when I try to access anything on the internet I get a "serve unavailable" error. I've tried everything in this thread with the exception of resetting the server. I'm staying at a hotel in Germany and they won't do it. I've used my iPad at different hotel here so I know it's not an issue with Germany.
Any help would be greatly appriecated.