iPhone 11 Pro Max phone ringer does not function

When my phone receives a call, the ringer does not function.

The mute button on the side is turned off.

The volume slider is at 100% and if I play a song, there is plenty of volume.

SOftware is up to date

Do not disturb is off

Silence is set to only when phone is locked

Calls are allowed from everyone and when I receive a call, it shows up on the screen, but no ringing at all.

When I connect to Car Play, the phone does ring on incoming calls. If that means anything.

What have I missed?