My mobile is just back from the repair centre after a few issues have been fixed.
It has now finally updated to Android 8.1 and July security patch.
However now the Bluetooth only connects to my car stereo if I select only phone and disconnect media.
I tried the other way round and the Bluetooth app on the phone closes every couple of seconds. Same if both are selected.
I have carried out 2 factory resets and no difference. It works fine in safe mode but then I can't use Audible for my audio books.
There are no non playstore apps installed. Battery optimisation is off for Bluetooth.
Any help and advice gratefully received. It worked fine in 8.0 and 9.0 is not available here in the UK on O2. I have tried.