The Astound (nee' RCN) tech, Juan, came to my condo today and helped discover some Extremely Wack Shit in my walls.
There are four rooms which have coaxial jacks in them. The feedline comes in into _yet another_ room, and then goes to three of the four; the fourth is daisy-chained with that one.
My modem wasn't working because it was in that fourth room and neither that or the room it was chained off of were connected. Juan reconnected them and also put a MoCA filter in front of the feedline so I can use the other jacks for MoCA.
I'm hyped, homeownership is excellent so far.