I can't install iOS 15.7.6 on my iPhone

What happens when you try?

Can you post a screenshot of the whole screen, it could reveal why you aren't able to update.

Make sure you:

• Are using a WiFi connection (not a hotspot).

• You have an active cell signal (You need both WiFi and cellular service to perform the upgrade).

• Are not using a VPN connection.

• Have your battery charged at least 50%. Better yet, keep it plugged in during the update.

• Do not have power save mode turned on.

• Do not have a beta version installed.

• You have at least 10 gigs of storage available.

Click on this link on what to do if you can't update your phone -

If your iPhone or iPad won't update – Apple Support (UK) If your iPhone or iPad won't update – Apple Support (UK)

The cellular issue is most likely the issue. You need both a WiFi and cellular connection to perform the upgrade. Try using a computer to perform the update.

Click on this link for instructions on how to update your phone using a computer

Update iOS on iPhone - Apple Support