Some of the iPhone fans may find that after upgrading the system firmware, the WiFi connecting function becomes grayed out or dim thus fail to turn on or off. We have sorted out some of the present feasible solutions which can solve the above problem. If you are still unable to turn WiFi on or off after attempting the following steps, the problem most probably would be hardware pseudo soldering. Please contact local Apple repair points.
Method 1: Verify that Airplane Mode is off
Method 2: Restart your iOS device.
Method 3: Update your iOS device.
Method 4: Continuously reset network settings for 5 times.
Settings-General-Reset-Reset Network Settings-Reboot
Method 5: Shut down your iSO device-Auto reboot by connecting to charger-WiFi restoration complete
Method 6: Restore your iSO device in iTunes.
Don’t forget to back up before restoring. Right click “device” on the left side of iTune interface then click “Transfer Purchases”. Re-jailbreak is needed after restoring.
Method 7: Blow hot wind about 2-3 minutes apart 1-2cm from the right side of the back camera then check WiFi before or after reboot.
Method 8: Shut down your iSO device-Wrapped with plastic film- Wrapped with newspaper(damp proof)-Freeze around 10-15 mins in the fridge- Unfold the newspaper and turn on the device with plastic film-check Wifi module.