The next thing that I would suggest is to reset all settings. You will not lose any data when you do this, but you will have to enter all of the device’s settings again. This includes having to enter all WiFi network passwords for all of the WiFi networks that you use. It’s not the nuclear option like restoring to factory settings, but it does take some time to enter all of your preferred settings again.
From the Apple support website regarding resetting all settings.
- Reset All Settings: All settings—including network settings, the keyboard dictionary, the Home Screen layout, location settings, privacy settings, and Apple Pay cards—are removed or reset to their defaults. No data or media are deleted.