Why is CarPlay failing in my used 2019 car: disconnects, touchscreen, Siri?

[Sofia33]

I recently bought a used 2019 car that has the factory infotainment system with Apple CarPlay, but the connection is incredibly glitchy. It disconnects randomly, sometimes the touchscreen becomes unresponsive, and Siri often cuts out mid-command. I've tried different cables, resetting the phone and head unit, and updating iOS, but the problems persist. For others who have dealt with unreliable CarPlay, what was the ultimate fix? Is this more likely a software issue with the car's firmware that needs a dealership update, or could it be a hardware problem with the USB port or the head unit itself? Are there any known compatibility issues with specific iPhone models and certain car manufacturers?