Found some suggestions on the internet as what do to with a problem like yours. Worth trying. Here are some:
--If possible,
try restarting your car's infotainment system, then try to connect again. If Android Auto has previously worked with your device and car, it is likely that the problem is with your cable. Try changing the cable to see if you can connect.
--Why does my Android phone keep disconnecting from Bluetooth in car?
Sometimes apps will interfere with Bluetooth operation and
clearing the cache can solve the problem. For Android phones, go to Settings > System > Advanced> Reset Options > Reset Wi-fi, mobile & Bluetooth.Apr 12, 2022
-Reinstall the Android Auto App
The Android Auto keeps disconnecting issue could be a result of the corrupt installation of the Android Auto app and reinstalling it may solve the problem. What is this? Upon restart, reinstall the Android Auto app and check if the disconnecting problem is cleared.
Here is a website that offers 15 easy solutions for a problem such as yours:
Fixing Android Auto Keeps Disconnecting - 15 Super Easy Solutions (convergeddevices.net)