So for future use, if I’m installing rj45 sockets each one will need its own cat5 from the router area? And as the routers only tend to have 4 ports, if I have more than 4 cat5 cables then I will need to use a PoE 8 port connected to the router and connect the cat5’s to the port switch?
Yes, you run each socket as a point to point connection, and use a switch (it doesn't need to be PoE unless you are wanting to power devices via PoE) to provide as many ports as are needed to be used.
Since you had to ask, I'm assuming you aren't familiar with doing network cabling ... properly. It is important to handle and terminate cables properly or you can badly affect signalling. In general, domestic installs have short enough runs that it doesn't show, but especially when you get to be using gigabit ethernet it really does matter. I've seen people kink and twist the cables - including one job where I saw the apprentice deal with the cable snagging in the box by simply pulling harder until the knot came out. I've seen people strip back 6 or even 12 inches of sheath and leave the pairs in disarray. I've seen the pairs untwisted too much. I've seen some really bad cases of split circuits* and/or not all cores connected.
If it's only a handful of runs, you can terminate the under stairs end in (say) a 4 socket faceplate or two. But generally you want a patch panel and a cabinet to mount it in - which also takes the other bits and pieces such as router, switch, possibly fibre ONT, etc.
To do this you WILL need some tools.
As a bare minimum you need a proper punchdown tool. Almost everything these days uses Krone terminals, so you need a
Krone punchdown tool - like the BT guys have. I can't say I've come across 110 terminals in a long time. NO, pushing the wires in with a screwdriver is not OK. You also need a way of testing things.
As a bare minimum, you can use a
cheap continuity tester where the lights come on in sequence on both ends - if they are out of sequence, wrong colour, or don't come on at all, on the remote end then you have a wiring fault. But these will not detect split pairs which happen if what you punch down doesn't match the wiring scheme for the connector, and which will absolutely kill the ability of the cable to carry ethernet. Without a proper tester you are into the same territory as an electrician that wires everything up, switches on, and if the lights work assumes it's all OK - network cables won't give you the big bang, but they will just "fail to work", or worse, "sort of work, intermittently". Ideally you'll use a proper
certification tester which will measure the actual performance of the cable and identify any faults - but you are into thousands for those.
* Worst I had to fix was where the "electrician" had cut back all the network cables (a number of units previously used by one tenant and sharing one cabling system were being separated back into separately rentable spaces) and terminated them onto a new patch panel without looking at the connection diagram. As a result, each socket on the panel had two pairs to one wall socket, and two pairs to a different wall socket. And nothing was numbered either. So I had to pull the lot off, work out which was which (
tone set is a godsend there), and re-terminate them properly.
No, however you can get an rj45 splitter pair that can allow 2 data links down a single cable.
I would absolutely not design the need for those into a job. They are useful to get out of a fix, but for one thing only support 100meg ethernet - gigabit needs all four pairs.
, if all you need to do is connect your single LAN cable to the two devices, then one of the two-port switches below would (allegedly) do the job. As supplied it needs 5V power from a USB port, so if there's power under the stairs you could use a USB power brick, or a 13A socket with USB, etc. or a handy live usb socket if there happens to be something there with one!
