Can someone explain this setup?

Question

We bought a house a few years ago, and it has ethernet ports in several rooms but I don't quite understand the setup. We have three rooms with ethernet plates: the basement, the master bedroom, and a bedroom that is my home office. The connection to the internet comes into the basement. Where it comes in, there's another ethernet port that says "BR", which I assume stands for "bedroom". In the master bedroom, there's another plate with two ethernet ports: one labeled "BSMT" (presumably basement), and one labeled "Office". Then, in the bedroom that serves as my office, there's another jack with a single, unlabeled port. There are images below of the three below.

I'm assuming that the idea is to allow wired connections in various rooms, but I am guessing. If my guess is right, how does it work? If not, any idea what the setup is for?

Basement plate:

Master bedroom plate:

Bedroom/home office plate:

Answer 1

As the network comes into the basement and there is only one route out of the basement, that is your main line. Wherever it goes you will either have a hub, a wifi AP, or both. A wifi AP with a hub built-in would allow the first segment from your basement to bridge to to the other ports for other computers or wifi APs.

Answer 2

What you have is some kind of mix between a so-called "Bus Network" and "Ring network" topology. What you would need nowadays is a so-called "Star Network" topology where all the "nodes" (plates) would go to one single location (usually to the router).

But forget the technical terms, they are just for reference if you want to read up on the matter. In your case I presume the connections are:

               [  Basement  ]       [  Bedroom   ]       [ Office ]
Landline <===> [BOTTOM] [TOP] <=1=> [TOP] [BOTTOM] <=2=> [ SINGLE ]

This is just a guess, you will need to test it. This was probably done to save time/cost on the wiring since it is simpler than implementing an actual star topology.

If my guess is correct this was most likely the previous setup:

               [     Basement       ]       [        Bedroom        ]       [     Office     ]
Landline <===> [B] <-> ROUTER <-> [T] <=1=> [T] <-> SWITCH/AP <-> [B] <=2=> [S] <-> SWITCH/AP

There will be no problem to continue to run it in the same way but there are two (minor) drawbacks to a "real star topology". The first one is that the first wall line has to be "shared" between all devices in the bedroom and office and the second one is that you need a switch to connect the office to the basement. This wouldn't be the case if all lines would end directly in a central place.

Unless you have an internet connection with "regular" bandwidth and you don't run a server in the basement that requires high bandwidth to the bedroom and office at the same time you should be fine.