CarPlay wireless stopping the iPhone cellular data connection after a few minutes

my CarPlay wireless worked fine for 2 years. Then about 2 months ago, after the bluetooth and wireless handshake with the CarPlay app, the apps in CarPlay work fine for about a minute and then the cellular data connection stops working. Any app on the CarPlay that uses a cellular connection (pretty much all of them) cannot function. You notice it on the Maps app as the street background disappears. If I pick up the iPhone and try to use an app on it, they do not work because the cellular connection has stopped working. If I go into the settings and turn off the wifi connection to the car, the cellar connection fires back up on the phone again and I can use the apps on the phone (like the Map app). If I start the wifi up and it connects to the car, CarPlay fires back up on the car head unit and it works for a min before the cellular connection stops again. The only way I can get CarPlay to work now is to turn off wifi and connect the iPhone with a USB cable as without the wifi connection to the car, the cellular data connection stays connected.

Not sure what changed to start this happening. I have tried the option to delete the phone from the car entertainment system, "forget this network" from the iPhone settings for the Car Wifi network and then reconnected like it was a new device, and the problem is still there.

I have seen this problem for other users over the years but no real solution to fix it. Looking for some ideas on how to fix this.