May I know more details? when you come back to your car, say after 30 mins parking or so , and you open then app and the two device simply won’t connect? Do you happen to have a screenshot for this?
Would you please try turn the airplane mode on and off first? This could help for most android users.
Removing device from app is the last step we shall ever ask a user to do. So sorry it had caused you such inconvenience.
Let me know if the problem persists or not, would be glad to help out.