I just tried it on mine. Went do the connected network then tapped the circled i, tapped Static and entered a valid static IP address different than the DHCP address, and filled i the same subnet mask and router and DNS. I then tapped wifi to backup out. It then reconnected and I verified that Safari worked. The I went back to the network and tapped the circled i and the static adress was srtill listed.
You can try:
- Reset the iOS device. Nothing will be lost
Reset iOS device: Hold down the On/Off button and the Home button at the same time for at
least ten seconds, until the Apple logo appears.
- Reset network settings: Settings>General>Rest>Reset Network Settings. Yo will have to rejoin all wifi network and re-pair BT devices.
- Reset all settings
Go to Settings > General > Reset and tap Reset All Settings.
All your preferences and settings are reset. Information (such as contacts and calendars) and media (such as songs and videos) aren’t affected.
- Restore from backup. See:
iOS: Back up and restore your iOS device with iCloud or iTunes
- Restore to factory settings/new iOS device.