I had some problems similar then the phone quit completely. They roll a truck and it turns out that a neighbor had signal problems so he put a filter on mine that killed my signals. Report on dslreports.com as their customer care folks monitor that. Senior customer support folks
I've been right every time they had problems and told them the exact problem they had and how to fix it.
Yet every time they say "sure... yup"
Oh well. I wish I had a another cost effective choice. Even Business Class won't get me what I need. They don't consider "real time" as a core part of their product any more.