I had FIOS installed in July 2015. The whole time, I have been experiencing fairly frequent (every 2-5 minutes) audio dropouts of approximately 1 second when viewing TV through the VMS1100 DVR. I have seen this behavior in live as well as recorded programming, though it seems that the issue does not recur at the same point in a recording if I rewind and replay. Some programs, such as live sports, seem to display the problem more commonly.
The audio is connected to a Yamaha audio receiver, and I have tried using both HDMI and, currently, optical digital output from the VMS1100. I do not have similar problems when using other devices connected via HDMI to the Yamaha receiver.