When this happened did you go into settings and look to see if it was indeed trying to connect to your network? I have had issues in the past where Remote failed to turn on my Apple TV or the printer never woke from sleep when I sent a document. A quick look in settings always reveals that I am connected to the neighbors wifi, instead of mine. There may be a network near you that is set up to require a user name and password.
Some things to try first:
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
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 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.
If any of the above solutions work, please post back what solved your problem. It will help others with the same problem.
First of all many thanks to both Mistimp and Texas Mac Man. All suggestions very much appreciated. One thing I did forget to mention in my original post was that when the iPad showed the need for User Name and Password to be entered there was no wifi signal showing on the iPad i.e. the typical wifi icon did not show at all. This is why I moved the iPad closer to the router. The puzzles are firstly that this happens very infrequently and secondly I have the iPad in exactly the same place.
I will now wait for the issue to happen again and try the resolutions posted above. I will, of course, post again to report any outcome. There may be some delay due to the infrequency of the issue, but I promise to post!
As promised an update. I have resolved the issue to some degree, but I am still puzzled by the problem. I still feel my resolution is more of a work-around rather than a final solution, but it might help someone with a similar scenario.
The iPad 4 again failed to find the home network, The screen showed no wi-fi icon and I was unable to access the internet etc. When I tried to log-on to my home network I got the "problem" screen again, asking for User Name and Password.
To resolve the issue this time I took the iPad closer to the router, turned the wifi switch in settings off then back on again. This time the wi-fi icon reappeared and I was able to access my home network without any need to log-on.
The obvious conclusion is the distance from the router being the problem, but my iPhone has no issue from the same position and neither does my partner's android phone and tablet.
I think my next step is to get an appointment with someone at the Genius Bar in my local Apple UK Srore. I will report back again if there is any progress from that appointment.
Ever since the last BTWifi-X has appeared in the list of Networks, when I try to connect to the Home Hub I, and anyone else with an iPhone/iPad in the house, we are asked for a user name and password. Every combination of user name and password is used to no avail. The BT account user name & password, the email user names passwords, the iTunes user names and passwords all fail. We can connect via a router extender which is hardwired to upstairs via an installed ethernet connection, or via BT Wifi app, but not to the hub itself. The computers (MS Windows) have no such trouble - what is going on and is there a cure?