2013 E350 Cabriolet Sat Radio and sound problems

My satellite radio operates normally for about 10 minutes and then shows "device unavailable". All other Command components go silent. They're running but with no sound available. When I restart the car after a rest everything works again for about 10 minutes. I suspect the Satellite radio module is failing but I can't find it in order to test or replace it. Can anyone tell me where to find the module in the car and how to get to it?