I found a solution and it works for me.
First u need to turn off the wireless projection on your android auto setting, then at your mobile wifi selection look for your head unit wifi and then connect it ( you need to know your head unit wifi password), after you connected, your phone might pop up a notification to use mobile data, after all these done, you can turn back on the wireless projection on android auto setting.
Before i just use the cable to let android auto finish all the bluetooth and wifi setting ,turn out the mobile data part dose not work, i guess the critical point is, system auto wifi setting will not work with the wifi assistance function and notification.
Please let me know if is working on your side
My Head Unit is CARLINKIT Audi Wireless Module.
First u need to turn off the wireless projection on your android auto setting, then at your mobile wifi selection look for your head unit wifi and then connect it ( you need to know your head unit wifi password), after you connected, your phone might pop up a notification to use mobile data, after all these done, you can turn back on the wireless projection on android auto setting.
Before i just use the cable to let android auto finish all the bluetooth and wifi setting ,turn out the mobile data part dose not work, i guess the critical point is, system auto wifi setting will not work with the wifi assistance function and notification.
Please let me know if is working on your side
My Head Unit is CARLINKIT Audi Wireless Module.