How can I fix Wi-Fi and cellular connectivity issues on my iPhone 13?

pattywats wrote:

AT&T carrier is not the problem. I have to keep turning iphone 13 off and on to get the internet - even for cellular and then only have temporary connection. Phone is only 1 1/2 years old. Wi-Fi not the problem. All Apple devices on network have internet connection.

Do you have a 3rd party VPN installed, even if you are not using it? If so, delete the VPN profile in Settings/General/VPN & Device Management/VPN. Don't just turn it off; delete the profile. If that fixes it, you can try reinstalling VPN. 

First, try a forced restart. If that doesn't work take it in to the Apple store to have it looked at.

• Press and quickly release the volume up button

• Press and quickly release the volume down button

• Press and hold the side button.

• When the Apple logo appears, release the button.

Force restart iPhone - Apple Support (IN) Force restart iPhone - Apple Support (IN)

Make an appointment at the Genius Bar to have it diagnosed.

Genius Bar Reservation and Apple Support Options - Apple Genius Bar Reservation and Apple Support Options - Apple

VPN is probably the most common cause of communication problems. Here’s the lowdown→VPN: What you need to know - Apple Community