To troubleshoot the wi-fi connections, use multi-tasking to close out all recently opened apps, then restart the iPad by holding the sleep/wake button until you see the "Slide to Power Off" screen. Then, after the screen powers off, press and hold the sleep/wake button until you see the Apple Logo. After the iPad finishes starting up, try to connect to wi-fi again.
If that fails, go into settings>wi-fi and tap the blue circle with the arrow found to the right of your network name. Then tap "Forget this Network". After forgetting the network, try to re-join. Alternatively, you can go to settings>general>reset>reset network settings. Then go back to wi-fi settings and try to join the network.
If it still will not connect, restart your wireless router. This is normally accomplished by unpluggin it, and then pluggin back in, but you may need to refer to your router's manufacturer for more specific steps. After the router restarts, try connectin with the iPad again.
Hope this helps!
Look at iOS Troubleshooting Wi-Fi networks and connections http://support.apple.com/kb/TS1398
iPad: Issues connecting to Wi-Fi networks http://support.apple.com/kb/ts3304
iOS: Recommended settings for Wi-Fi routers and access points http://support.apple.com/kb/HT4199
Additional things to try.
Try this first. Turn Off your iPad. Then turn Off (disconnect power cord for 30 seconds or longer) the wireless router & then back On. Now boot your iPad. Hopefully it will see the WiFi.
Go to Settings>Wi-Fi and turn Off. Then while at Settings>Wi-Fi, turn back On and chose a Network.
Change the channel on your wireless router (Auto or Channel 6 is best). Instructions at http://macintoshhowto.com/advanced/how-to-get-a-good-range-on-your-wireless-netw ork.html
Another thing to try - Go into your router security settings and change from WEP to WPA with AES.
How to Quickly Fix iPad 3 Wi-Fi Reception Problems
If none of the above suggestions work, look at this link.
iPad Wi-Fi Problems: Comprehensive List of Fixes
Fix iPad Wifi Connection and Signal Issues http://www.youtube.com/watch?v=uwWtIG5jUxE
Fix Slow WiFi Issue https://discussions.apple.com/thread/2398063?start=60&tstart=0
Unable to Connect After iOS Update - saw this solution on another post.
Note - When troubleshooting wifi connection problems, don't hold your iPad by hand. There have been a few reports that holding the iPad by hand, seems to attenuate the wifi signal.
If any of the above solutions work, please post back what solved your problem. It will help others with the same problem.
Ok i have an iPad3 64GB and wasn't having this issue until i rebooted my device. Ok now this started happening i tried restarting the device, no luck ; what did i do ??? i went to settings then tapped on the blue icon on the network tapped forget network. Ok now this is trick worked for me and am sure it will also work for you. Ok now join the network wait for some few minutes don't tap nothing !!! after lets say 2 minutes double click home button end the settings app. Open up safari and there you go your iPad should stay on the network
ps : sorry for my english