Problems with sound randomly going silent for a few seconds and coming back several times

We recently moved and had two new boxes put into our new apartment, one upstairs and downstairs. The picture is great, but the sound keeps going in and out. The Sound will be fine, then randomly it will go silent for several seconds and then come back. This happens several times no matter which different audio we set up on both boxes/tvs. I'm getting tired of this. We paid a lot of money to get good service, not the sound randomly going out every so often. I keep resetting the sound every time I watch my tv hoping it will fix it, but no such luck. Do I have to keep unplugging the box every day? This is getting ridiculous. I shouldn't have to do this every time I watch tv. It seems like ever since we moved, we've had nothing but problems with xfinity, which includes different agents giving me different prices, getting different answers on USB adapters and now how to deal with these annoying sound issues. Please fix the sound.