First thing I would check is that the demarc(where the coaxial line coming from street is connected to your electrical ground) has a weather enclosure box on it. If there are any splitters in there, make sure they aren't waterlogged. Next, I would suggest having a technician investigate your tap, which is your connection at the street.
As for it being the whole node, are you aware of others in your area having the same problem?
Not sure about that last question, but thanks for the tip about the de-marc. Will check that out today.
When you check the demarc, if you do have a enclosure box, make sure the coaxial coming from the street is looped in such a way that water doesn't drain into it.
