So, don't know if this will help, but I've been dealing with a similar problem in my '16 3170 for the entire 10 months I've owned it. I believe I've found the issue...have it in with the dealer now, and this is one of the items I've asked them to fix. This will be the fourth (yes, fourth) time the fix will be attempted. This time, hopefully, will be the charm, as I think I've figure out what's going wrong.
Same symptoms...every once in a while the sound cuts out...then it comes back on after a few seconds. Happens more when the vehicle is moving. Dealer has thought...were absolutely sure..they'd fixed it before...on one trip they even swapped out the entire head unit...but 10 miles up the road it happens again.
My son and I decided to take a look at the wiring. We pulled the engine cowl...and were absolutely dismayed at what we found. You look under that cowl, there's just a mishmash of wires all suspended above the transmission housing, just everywhere. FR doesn't tuck the wires, wrap them, or do anything else to tidy up the installs. The head unit connects to the external speakers through a harness. No surprise there. But the harness is just suspended there, sagging down to just a few inches away from that hot transmission and engine. My theory is that the harness jiggles around and every once in a while gets loose enough to break the connection. Then you hit another bump and it bounds around a bit and waddaya know, you have music for a while.
I've asked the dealership to clean up that mess, wrap and tie the wiring, get all that stuff off the engine/tranny. There's really no excuse for that crap quality control.