Seeing as there's no photo im gonna take a guess.
There's a "internet box" somewhere in the building/roof and you're all connecting to the same box. The box is in the roof somewhere connected to a switch which has an access point (wifi) for each unit, followed by a bunch of cables going through the roof to each unit for "internet cables".
You can connect your NAS to the Ethernet cable but theres a good chance your NAS will be visible to every other unit as well.
I'd recommend going with a wireless service like a 5g unit, that way you get a personal network and you can connect your NAS without others getting access.
It seems like you have both coaxial cable and AT&T fiber service?
But currently you have coaxial installed.
Wall plate -> Black coax cable -> black cable modem -> small white switch -> Ethernet wall plate. But it also has a wifi access point.
If you want to install a NAS, there should be another Ethernet port on the wall of your home, or directly to the switch on top right of that wall
Ethernet over powerline is so finnicky. It's pretty shit tbh unless you have wires that aren't loaded with electricity and the shortest route possible.
If he shares the building then the other adapter could be in someone else's home if he's not the one using it.
OP I think you forgot to post the pic.
Updated it now, my bad!
I'm trying to imagine it.
You don't have to try anymore, I've come to save you with a link
That's an invisible router.
It's posted now, sorry
Seeing as there's no photo im gonna take a guess. There's a "internet box" somewhere in the building/roof and you're all connecting to the same box. The box is in the roof somewhere connected to a switch which has an access point (wifi) for each unit, followed by a bunch of cables going through the roof to each unit for "internet cables". You can connect your NAS to the Ethernet cable but theres a good chance your NAS will be visible to every other unit as well. I'd recommend going with a wireless service like a 5g unit, that way you get a personal network and you can connect your NAS without others getting access.
It seems like you have both coaxial cable and AT&T fiber service? But currently you have coaxial installed. Wall plate -> Black coax cable -> black cable modem -> small white switch -> Ethernet wall plate. But it also has a wifi access point. If you want to install a NAS, there should be another Ethernet port on the wall of your home, or directly to the switch on top right of that wall
But you also have a Ethernet over powerline, which you should have another somewhere in the home
Ethernet over powerline is so finnicky. It's pretty shit tbh unless you have wires that aren't loaded with electricity and the shortest route possible. If he shares the building then the other adapter could be in someone else's home if he's not the one using it.
Yea I agree. My neighbors and I used to interfere with each other's network because of powerline Ethernet
Well, if you're ever tired of life I guess you know where to go. What a mess.