Hi I had the same problem working fine then all of a sudden stopped kept telling me unable to connect and make sure my Bluetooth is on. It wouldn’t even pair to my phone even tho car is giving me a pair message on car screen but not on my phone. So I reset all phone settings and nothing even tired factory reset my iPhone still didn’t work. But I’ve finally fixed it here’s how I did it.
Before you get in your car go into carplay in settings on your phone and forget the car you use to connect your phone to so it’s all blank and come out of CarPlay app. Make sure VPN is off if you use it.
When you get in your car turn off Wi-Fi and connect via usb cable and press the voice button on steering wheel and delete your phone that’s on there then search for the phone again BUT NOT through CarPlay app on your phone.
It should give you a message saying Wi-Fi will give you better location connection click ignore this. It should ask to pair if it dose carry on with this. If not still try this.
Then pull down the screen on your iPhone top right, and click on the small Bluetooth icon and then click it again where its says Bluetooth on.
Click on Bluetooth settings it should bring a page up with my devices that you have used before.
At the bottom it says other devices wait for your phone to discover your car will take about 30 seconds and click on it should give you a pair message on your car screen as well as you phone click both. Go into CarPlay app and it should be there again and working fine. Turn on Wi-Fi and you’re good to go.