I know some of people facing Wi-Fi connection problems after iOS 6 update.
There are a lot of threads and solutions about this problem. But mine is bit different.
I have an iPad and after i update to iOS 6 there wasn't any issue about Wi-Fi connection.
I surfed all day long , upload and download many thing using my home Wi-Fi network.
Today I couldn't connect to my campus' Wi-Fi network. I turned on my phone's hotspot
and iPad connected to my phone's cellular based network just fine. I tried to connect directly with my phone to campus' network and my phone also connected just fine. When i searched the web i saw a lot of Wi-Fi issue thread about iOS 6. I have read all of them but my problem is bit different.
My campus' network is using a Captive Portal thing to get internet access. So you have to enter your user id and password after you connect wirelessly.
When i was using iOS 5.1.1 iPad was connecting to network automatically and waiting for me to open safari or chrome and enter my id and password.
But now after i joined to network a window pops up and and wants me to enter id and password (not an apple page, my own university page) and at the same time connection drops and wi-fi icon get lost so my log-in info can't send. I open and wi-fi panel and connect again and same thing occurs. Pop-up window and connection lost. This is a vicious cycle i think and everybody using iOS 6 in my campus facing same problem. iPhone iPad iPod Touch users can not connect because of this problem.
I have done everything that written about common Wi-Fi issue.
I am sorry about my broken English BTW.
Waiting for your help.