Hi all, moved into a prewired house (built in 2003) and am trying to get my office connected to my router. The office has one of these green wires terminated at a wall jack while the rest of the house has the blue, which I just put new terminals on and plugged into a 10 port switch, then my router without issue. Question is, what is this thing that all the green CAT 5 wires connect to? The bulk of the wiring is strung through the attic space and drops down into the access panel in my closet. Do I need this thing or does it serve as some sort of bus? I just see wires come in and wires going out. Do I need to disconnect it and identify the office wire or can this be used somehow?

Thanks and any help would be appreciated!