That can be caused by a few different things. Most are connection related and some are to do with the outside connection. In rare cases it's the set top box. It's also rare for it to be an area wide issue as those are caught pretty fast.
One reason I ask about other devices like ethernet switches is that in the past when I had a similar issue, it turned out that the ethernet switch I was using had started malfunctioning. To the PC connected didn't show any issues but the set top box was more sensitive. Swapping out the switch fixed the freezing in my case, though switches failing is also quite rare.