Hi F700W,
It looks like you are experiencing issues with the sound on your CarPlay with your iPhone 11, after trying additional cables the issue remains unless you turn off mobile data. We understand the need to use the audio and hands-free features CarPlay offers for safety while traveling. You've come to the right place for help.
Does this happen with content that is downloaded on your device or content that is being streamed from Apple Music or a third party app? Are you using the original Apple cable that came with your iPhone 11 or third party Apple branded cables? We'll want to restart your iPhone and also follow the steps below to forget your car from the stereo and for get the car from your Settings on your iPhone.
iPhone - Settings > General > CarPlay > [Stereo Name]
Vehicle - check the user guide for the vehicle
Try to set up CarPlay again.
Keep us posted in the community on the outcome of those steps. Any additional details or messages you receive when using those steps to see if the community can offer more help.
Take care!