My brand new (~3 months old) Galaxy A71 has recently started showing an error message: "The connected USB device isn't supported."

The main problem with this is that there is no USB device connected, the USB port has nothing plugged into it!

If I restart the phone whilst the charger is connected, the message doesn't appear until I disconnect the charger.

Since the message has appeared, I am unable to connect the phone to my car to use Android Auto.

I have tried a factory reset, it did not solve the problem.

Any suggestions greatly appreciated!