I find that pausing for a second brings sound back after resuming play. Also, rewinding and replaying brings sound back in the same segment that just had no sound so it's not an external connection issue but instead something with my in-home equipment.
If I were to guess I'd say the sound drops out when the STB or Multi-Room DVR are being heavily taxed with other tasks and the processor can't keep up.
Is there a solution to this aside from requesting a new DVR Multi box?