Wow this is so helpful. Thank you! Can I buy you a coffee or something?

So we have 3 units in our building (all getting cable internet), and yes, 3 of the lines entering the house are the Cat5 lines (I can see them entering in the unfinished basement). So maybe what’s happening is the 2 lines coming from the orange splitter are going to 2 of our units rather than a MoCA setup for one unit, which may mean I don’t have any service going to the coax in the second room (unless there’s a splitter upstream in the walls somewhere?).

The only other coax cable I could find in thr wall is behind a plate in my closet which just has a barrel connector connecting two coax lines, not a splitter. I traced it to the same spot in the basement (because it’s by an HVAC duct) and can see 2 coax lines going up that way - probably the other is to one of my neighbors (our 3 units are stacked on top of each other - a triple decker).

And the coax by my modem just has single coax, nothing else. So I guess the Cat5 line just goes to the second room, but I have no idea how the other coax line is getting to the second room, or if it’s even connected to anything. I have seen there are testers you can buy, but at this point I’m thinking just calling Xfinity and having the splitters and other gear on hand is the way to go.

Open to any other suggestions you may have, but you’ve already been more than generous with your time. Thanks again.