Any ideas on why the sound on my iphone 6S would just stop working until I shut the phone off completely and turn it back on? It doesn't stop while I'm listening to something but rather I will be watching a video or whatever and everything is fine and then a little while later, after the phone has been doing nothing, I try to watch a video or listen to a pod cast and there is no sound. Only a restart or shut down/turn back on solves the problem.