Hi Guest. I have the same problem.
However for me it *was* working when I first connected my phone to the headset.
It was really good to use. I said navigate to contact, send text, call contact, ask google a question.
Then it stopped working for no reason I can understand after about a week.
Talking to the man who installed the headset, I have tried several different things:
Replaced the USB lead with the original Samsung lead (instead of the cheap Chinese lead I had).
Uninstalled Android Auto on the phone then re-installed it.
Checked I had Android Auto able to work in Background Data mode on the phone.
He suggested I could reinstall the Android OS but that's a last resort because of the time it takes.
He also said I might have bought a non-UK phone but I don't know how I can check that.
He also suggested trying it with my van near my home wifi to confirm it's a data problem.
I notice although the phone shows 4G the headset shows LTE.
So I am looking for an answer to the same question as you.
100 people have looked at your post but so far no one has replied - I'm looking for expert help too.
Can anyone help?
Details:
Mercedes Vito van, Samsung Edge 7 phone (2nd hand from Ebay), Pioneer F77DAB headset.