(1) Try and Force Restart your iPhone EXACTLY as shown below and see whether that resolves the issue:
- Press and quickly release Volume UP button
- Press and quickly release Volume DOWN button
- Press and Hold the SIDE button until an Apple logo appears and then release the Side button (Can take up to 20 seconds. (DO NOT release Side Button when invited to Slide Power OFF).
(2) If the above does not work then - Reset Network Settings. Open Settings ➡️ General ➡️ Transfer or Reset iPhone ➡️ Reset ➡️ Reset Network Settings: You may have to re-enter all the previously known Wi-Fi Network passwords again.
Axel F.