After update of my Iphone4S to the latest version 6.0 I encountered a serious bug. Wifi stopped working 3 days after the update. Button to turn on and off Wifi is gray and not active. After several restart problem seemed to fix it, but it works for some time before relocked. I can not find a way to return the old version 5.1.1, without I kept my custom file *.shsh, I had not done. Now I still have to wait for a new version of Apple: (