I have had Bluetooth problems with my beloved iPhone for years. I think I may have found the solution. Go to Settings, then Bluetooth, then look at the info for the paired device, and you’ll see something I never saw before, an option to define the kind of device it is; i.e., headset, speaker, etc. Once I did this my Bluetooth problems appear to have been solved. BTW if my info is stale, my apologies.