Bluetooth disconnects when I turn off the car

I have a Kenwood car stereo. Though I have paired my iPhone, every time I turn off the car, the bluetooth connection breaks between the stereo and iPhone. When I turn car back on, stereo display says "AUD DISCONNECT" which means no bluetooth/phone connection.

I then have to go to my iPhone bluetooth settings, and scroll down to my car stereo, which says, "Connected" though it will not play music, and the stereo says, "Aud Disconnect."

I have to hit the "i" and "disconnect" the phone/bluetooth.

Back to Bluetooth, scroll down to car stereo and hit "connect."

Then it will connect.

My question is: how can i avoid going through that every time and just keep the phone and stereo connected. At least have the iPhone reconnect automatically and actually play music (it seems to be automatically connecting according to the iPhone, but not according to the stereo).

anyone else have this situation?