Ethernet Networking to Multiple Walls from Conduit

In my Conduit Closet, I have an ethernet cable coming in from my ISP (WAN). In the same closet, there are 3 other ethernet cables (one to each room in my condo), and they are wired to an ethernet jack.

I bought 65ft steel wire fish tape to fish the ethernet cable from the conduit to the "Office" and into a Keystone Ethernet Jack/Outlet on the wall. Then I wired the router to that outlet (router doesn't fit in the conduit box).

Now because I can only have the ISP cable going through to the router there, it means the other ethernet ports have no connection (Wiring: [C] -- [E] in diagram below). So Room #1 and Room #2 have no internet via Ethernet.

Layout


#1. My idea was to put a small Switch in the Conduit Box in the closet, then wire Room #1 & #2, and the router to the switch. I'm not so sure that would work though without some sort of special switch?

#2. So my second idea was to get a smaller router like the Unifi Edge Router (ER-4) and put it in the Conduit Box in the closet, then wire Room #1 and #2, and the Office Router to that ER-4.

But that might cause a problem is Office Router is wired to the ER-4 router? What if I wanted a router in Room #1 and the existing Router in Room #2 acting as a mesh via Ethernet? Would it be a problem that they both go through the ER-4?

For clarity, I want to put a Unifi Alien (or Dream machine) in "Office", and also one in "Room #1", and have them seamlessly wifi mesh via the ethernet cables going to both rooms.

Idea-2

#3. Third idea is to run another wire from the "Office" which goes backwards to the Conduit Box and from there connect it to a Switch. Then connect all other rooms to that switch. This might be counter-intuitive since I have to run another wire to the same room and if I were to move the initial router from that room, then I'd have to rewire the place :l

Idea-3

What do I need to do? OR how should I do it? Is there a better way?

Note: I have reduced image sizes, you can tap on the images for a larger (clearer) view.

I would do Idea #2, but I'm not sure if I would have double NAT issues :(


Solution 1:

#1. My idea was to put a small Switch in the Conduit Box in the closet, then wire Room #1 & #2, and the router to the switch. I'm not so sure that would work though without some sort of special switch?

In other words, your plan is to have the same cable (office—closet) carry two networks at once (from your router's perspective, both the "WAN" and "LAN").

This is easy to configure but does need a somewhat more special switch – you would need to use switches supporting 802.1Q VLAN tagging on both ends of the cable to keep the two networks separate, i.e. to prevent your router's LAN DHCP service from confusing its own WAN DHCP client and such.

(If the office router itself supports VLAN tagging, that works too, but I'd still prefer two switches just for configuration symmetry.)

#2. So my second idea was to get a smaller router like the Unifi Edge Router (ER-4) and put it in the Conduit Box in the closet, then wire Room #1 and #2, and the Office Router to that ER-4.

But that might cause a problem is Office Router is wired to the ER-4 router? What if I wanted a router in Room #1 and the existing Router in Room #2 acting as a mesh via Ethernet? Would it be a problem that they both go through the ER-4?

For clarity, I want to put a Unifi Alien (or Dream machine) in "Office", and also one in "Room #1", and have them seamlessly wifi mesh via the ethernet cables going to both rooms.

In this case, it would be best if the ER-4 was the only router, and everything else just provided Wi-Fi as an access point – in other words, either the office's Unifi Alien is set to "bridge mode", or you use the dedicated Unifi access points instead. (This doesn't look like an option with UDM, though.)

If you don't do this – yes, double-NAT is somewhat of an issue, but more importantly, seamless Wi-Fi roaming kinda requires all access points to be in the same subnet. If you have the same SSID everywhere, but parts of it are behind one router and parts behind another, your connections and streams will die whenever your device decides to roam. (This would still apply even if you didn't have double-NAT.)

#3. Third idea is to run another wire from the "Office" which goes backwards to the Conduit Box and from there connect it to a Switch. Then connect all other rooms to that switch. This might be counter-intuitive since I have to run another wire to the same room and if I were to move the initial router from that room, then I'd have to rewire the place :l

Well, there is nothing unusual in having two Ethernet ports going to the same room. If you're worried about re-wiring, then run a second Ethernet cable to every room. Result: all rooms have two Ethernet ports going to them, which is a completely normal thing in itself.

I'd say this is the best option, since it doesn't need any special router configuration or hardware, and a second Ethernet port might be useful in other ways not limited to your specific situation.