I too have been experiencing connectivity issues since FIOS was installed in November. I have three sets, the main box and two STB. The main box and the STB in my master bedroom works fine. However, the STB in my daughter's room has not functioned since installation. I have called Tech Support, had a new line installed to that room ($125.00) and have swapped out the main box and the STB multiple times, all at the suggestion of Verizon tech support. Nevertheless, the system still does not function. Although tech support reboots the system and gets the TV functioning it goes off line within a day or two. I had Comcast for 22 years without a problem, FIOS has been nothing but a nightmare and to make matters worse, now that its installed and I'm locked in, they simply don't care.
Tech Support simply follows a script and to make matters worse they don't even look at the history of the chat logs. They repeat the same script as if you're the **bleep** who can't connect cables correctly and the system is infallible.