We are all saying the same thing
There appears to be 2 cables in picture 1.
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Can you post a picture of the other end of the cable that goes to the living room? Is it near the master socket?
There are 2 cables shown in picture one, is one of them the cable that goes to the living room?
If the other end is not connected to the master socket and is just hanging loose, I suspect it is also an RJ11 and the previous occupants have simply unplugged it and removed the filtered faceplate from the master socket.
If that is the case, either just fit a filtered faceplate to the master or use a filter to convert the RJ11 to a phone plug to connect to the socket in master.
When you say the connectors "seem like", how have you determined this? An RJ11 connector will fit snugly into the grey port on the Hub. It will also fit into a yellow LAN port but won't be a good fit. An RJ45 connector will only fit into a LAN port.
So have you traced this cable outside & back in again, so that you're certain it's the same cable? It's all a bit odd & highly unusual to mix RJ45 & RJ11.
I've just noticed something odd on the cable that almost looks like a second connector. What is it?
Hi again - so the end of the cable you can see there is definitely RJ11 because it fits nicely into the corresponding port on the hub. This cable goes outside the house and then back in under the stairs and is RJ45 at the other end. Can’t understand why that’s the way it is, to be honest. The part you’re pointing to isn’t really anything - it’s just something that the wire is fed through.
I’ve had to place the Hub under the stairs because that’s where the master socket is. What I haven’t been able to test yet is whether the TV box will run off the Wi-Fi fine (waiting on a TV delivery) - it’s about 5m away from the Hub
I can't conceive of any way a setup like that would have worked. Are you able to ask the previous owner?
You can get an RJ45 to RJ11 adapter, but that ideally needs a filtered faceplate on the master socket. Although presumably your currently using a micro filter, which would do. Maybe you could ask what happened to that too? But even then we have no idea what the wiring configuration may be in that cable, so still may not work.
See how the WiFi connection works out. If no good you can get a cheap RJ11 crimper from the likes of Amazon to replace that RJ11. Or check locally for someone who could do it for you.