There are several threats about this issue, see https://forums.ubports.com/topic/457/the-bluetooth-thread/18 and the files on github (e.g. https://github.com/ubports/ubuntu-touch/issues/766)

My phone is a bq Aquaris E5HD ubuntu edition and now loaded with UBports image. My car is a Citroen C4 Picasso with the MyWay system from Harman. The version of this system is rneg_D_R50b_R50.03. That should be the newest one.

The behaviour is like this:

First when the two sides dont now eachother and starting the connection/ coupling from the car, all is working. It is possible to make calls and to see the addressbook of the phone.

After this when trying again the connection is not made anymore.
The phone says that the car is connected, but the car says the phone is coupled, but not connected and connection is not possible.

Without updating to android 8.0 it will not work, because the bootloader is not suitable.

The Sony Xperia X F5122 has working dual SIM too.

@cliffcoggin Yes, it is (old) Canonical software, but you can use it for UT.

@antidroid You can always install an older image from the image server by using ubuntu-device-flash.

bq aquaris E5 HD ubuntu edition since 2016.

Please see here: https://github.com/Halium/projectmanagement/issues/103

Without updating to android 8.0 it will not work, because the bootloader is not suitable.

Yes I did. But I don't know how. It's long time ago... Recently I had the same issue again and the cause was the wrong phone no.

No, the port is not abandoned. The Xx is now a community device with devel channel and gets updates.GPS is working fine.

I had the same issue a time ago. For me it helped to delete all parts via UTTT.

Thank you also @fredldotme. That sounds great. I'm very eager.