Many people have reported that their iPhone forgets Wi-Fi passwords. It seems that this problem primarily affects Netgear wireless routers. Users are also reporting that as soon as the Wi-Fi connection is lost, or the phone goes to sleep, the Wi-Fi password has to be re-entered.
Fix
Please try using the following tips below until you resolve your issue:
- Reset your network settings by tapping Settings > General > Reset > Reset Network Settings.
- If you’re still having problems, try Settings > Wi-Fi > Other > Other Network and add your Wi-Fi information manually.