I don't know if any of you have experienced this but using wireless Apple Carplay in conjunction with Apple Music kept pausing part way through a song, only to resume a minute or so later and then stop again. While this was happening, the little buffer wheel was spinning next to the play next UI. Even though my phone had a full 4G signal.
I found a fix for this. Apparently, Carplay is trying to default back to the car's E-Sim. When it can't establish an internet connection it goes back to the phone's internet connection, rinse and repeat.
Fix 1: Buy some data with Cubic Telecom so the car's E-Sim has some data. Alternatively, if you haven't already, activate your free 1Gb data pack which is what I did and Apple Music works like a charm.
Fix 2: Go into the infotainment settings and disable the E-sim. Then Carplay will not try to connect to the car's internet. Apparently, you can still use navigation and remote software updates with the E-Sim disabled but I haven't tried this yet.
Hope this helps someone as I have been ripping my hair out over it.