If you are facing the TFW on iPhone “Data not working” error then follow these methods to fix this error on your iPhone:-
1. You can long press the power button and then select Restart from the menu to restart your iPhone.
2. You can turn on the Auto-update feature or check for Firmware updates.
3. You can turn off your VPN if it is causing trouble.
4. You can also remove and re-insert the sim of your iPhone.