オリジナル投稿者： Hugo K ,
The issue might be either hardware- or software- related. If it is a hardware problem, your iPhone Wi-Fi switch under Settings > Wi-Fi will be turned off and/or greyed out (unable to be turned back on). This happens especially on iPhone 4 and iPhone 4S running iOS 6 and iOS 7 as the Wi-Fi radio chip overheats. Not much to do here except to take it to the Apple Store for replacement. If it is a software issue, it can get resolved by cold restarting the iPhone and/or by resetting your iPhone network settings via Settings > General > Reset > Reset Network Settings.