Try this - Reset the iPad by holding down on the Sleep and Home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons. (This is equivalent to rebooting your computer.)
For wifi, some things to try:
1. 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.
2. Go to Settings>Wi-Fi and turn Off. Then while at Settings>Wi-Fi, turn back On and chose a Network.
3. 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
4. Go into your router security settings and change from WEP to WPA with AES.
5. Renew IP Address: (especially if you are droping internet connection)
• Launch Settings app
• Tap on Wi-Fi
• Tap on the blue arrow of the Wi-Fi network that you connect to from the list
• In the window that opens, tap on the Renew Lease button
6. Potential Quick Fixes When Your iPad Won’t Connect to Your Wifi Network
Wi-Fi Fix for iOS 6
iOS 6 Wifi Problems/Fixes
How To: Workaround iPad Wi-Fi Issues
Another Fix For iOS 6 WiFi Problems
Wifi Doesn't Connect After Waking From Sleep - Sometimes increasing screen brightness prevents the failure to reconnect after waking from sleep. According to Apple, “If brightness is at lowest level, increase it by moving the slider to the right and set auto brightness to off.”
Fix For iOS 6 WiFi Problems?
Did iOS 6 Screw Your Wi-Fi? Here’s How to Fix It
How To Fix Wi-Fi Connectivity Issue After Upgrading To iOS 6
iOS 6 iPad 3 wi-fi "connection fix" for netgear router
Apple's iOS 6 Wi-Fi problems
How to Boost Your Wi-Fi Signal
Troubleshooting a Weak Wi-Fi Signal
How to Fix a Poor Wi-Fi Signal on Your iPad
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
WiFi Connecting/Troubleshooting http://www.apple.com/support/ipad/wifi/
How to Fix: My iPad Won't Connect to WiFi
iOS: Connecting to the Internet http://support.apple.com/kb/HT1695
iOS: Recommended settings for Wi-Fi routers and access points http://support.apple.com/kb/HT4199
How to Quickly Fix iPad 3 Wi-Fi Reception Problems
iPad Wi-Fi Problems: Comprehensive List of Fixes
Connect iPad to Wi-Fi (with troubleshooting info)
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
How To Fix iPhone, iPad, iPod Touch Wi-Fi Connectivity Issue http://tinyurl.com/7nvxbmz
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.
Wi-Fi or Bluetooth settings grayed out or dim
If any of the above solutions work, please post back what solved your problem. It will help others with the same problem.
Wow, thats a lot of links. However, after going through most of them i have found that the thing that has helped a LITTLE bit was to do a reset of the network settings only. Which makes sense to me, since my iphone, sony xperia, mac air, win7 lappy and vista pc all work fine without interference from the same physical location in the house as the ipad, which has problems after the ios6 upgrade. I had already ruled out the router or channel interference anyway, and had tried different manufacturers routers, different dbi antennas, placement, etc. none of the links above identified this step as a possible fix, so i cant mark that as an answer. Anyway, there is still a drop out issue.
An interesting fix was to disable proxy, which i DO use on some networks - but typically i am proxying through Charles on my mac for app debugging purposes. No proxy on this network. Didn't help anyway.
Post-network reset the dropouts now only occur on streaming items such as youtube or airvideo; general web traffic generally does not cause the network to drop. When the network drops out, other devices still continue to operate, so the dropout is limited to the ipad itself, not something in the router.
I have tried the power+home button reset thing which i had independently seen as a fix for the home button not working, but the home button still does nothing other than stopping wiggle mode, after a reset or power down the behaviour does not change, so it isn't a case of too many tasks running or so on. It is something ios6 has done to my ipad.
It did go to sleep this morning, too. Was wifi somehow holding the screen so it wouldn't sleep? Doesn't sound logical but resetting the network let the ipad sleep. Dumb, yet another ios6 issue perhaps? No idea.
So far it seems like it ha been a bad move to upgrade, but it is done and for some reason we cant go backwards again.