This is a strange situation and I doubt anyone will have any solution, but I’m hoping maybe I’m wrong.
We updated my son’s iPhone from a XS to an 11 Pro.
Since then, it will not connect reliably with his 2013 Dodge Dart (the entertainment system is called “UCONNECT”).
Apparently the must be some kind of difference in the Bluetooth between the two iPhones, although I haven’t seen much about that online.
Sometimes he can get it to pair, but once the car is shut off, it won’t reliably reconnect.
This worked flawlessly with his XS.
We’ve tried rebooting the iPhone, un-pairing / re-pairing it with the car, we even brought the car to the shop to see if there was a software or firmware update available for the car radio system.
I thought that plugging the iPhone in via USB would be an alternative, although not nearly as convenient. Turns out that the Music app on the iPhone is completely stupid when hooked via USB. It stops whatever is playing, and starts playing his music library from A-Z. Apparently this is a long-standing issue with the music app on the iPhone and USB connections to cars, but nothing has been done to fix it. (Maybe Apple assumes everyone will eventually be using CarPlay?)
Anyway, this is super frustrating and aggravating.