This may be a little niche - but I have the Kenwood DNX516 after-market head unit in my 2013 Tiguan.
It's always worked really well until I started using the CarPlay functionality. I assumed I had a loose connection (it needs the iphone plugged in by cable) as a few times per journey it would pause and need the phone to be disconnected & reconnected, or a wait of around 2 minutes for it to sort itself out and reconnect.
I've just had the head unit out and double checked the connections - the USB lead uses a non standard USB connector into the head unit then gives two cables (one iphone/ipod, one standard USB). It seemed to be clipped in pretty well.
I've run the available firmware updates from Kenwood but that didn't change anything.
I've recently been driving a Seat model with integrated CarPlay as my Tiggy was in for bodywork repairs after a van drove into it - that seemed to work with no issues for car play so I don't think it's anything at the phone end...
My gut feeling is that the USB cable is probably still the culprit but before I pay the £35ish for a replacement (had the head unit about 3 years so out of warranty) just wanted to see if anyone else uses this head unit + an iPhone and recognises similar symptoms?
Any thoughts appreciated,