Question Adding ethernet ports with the use of a switch


Aug 25, 2014
Purchased a relatively cheap ethernet switch to use as an expansion of ethernet ports from my current router.

It gets a bit more complicated as we have internal ethernet routing in the house, which means an ethernet cable runs from router to the wall, travels internally to another ethernet port downstairs where I have two devices - A TV and a PC that I wish to connect to that same ethernet port.

This is where the switch came in. Individually both the PC and TV connect fine using the downstairs ethernet port, but when I plug them both into the switch neither of them connect and the PC comes up with a networking error along the lines of "LAN doesn't have valid IP configuration" or something along those lines.

I am in the UK and have a BT home hub 5 as my main router and the switch I purchased was a D-link DGS-105. I have another two PC's and a wifi extender in another room connected via ethernet too.

Any help would be appreciated
It should be that simple.

You should see lights on all the ports. I would take the switch and a short cable and plug it directly into the router just to be sure it is not the in wall cabling.

It almost has to be a cable issue someplace. Unless the switch is extremely old you can use all straight cables no crossovers needed.
It has to be something the switch does not like with the in wall cabling. I will assume you have tried other ports on the switch but it is unlikely a bad port.

It could be some issue with auto negotiation of the port speed which is why you want to try a short cable to the router to be sure the router can actually talk to the switch.

Even if there was a problem with the switch there is nothing you can do but toss it and buy a new one.

Cables are really strange at time. They can work with some devices but not others. There can be a wire just slightly loose and it connects well enough for some device but not others.

It can be either end unfortunately. If the wall jacks use keystones it should be pretty easy to check that all the wires are tight punched down. You can careful use a small screwdriver and push the sides down, do not push directly over the center of the connector you need a special tool to do that without damaging the connectors.
Ethernet switches are just about as idiot-proof as anything can be. There is something wrong with your cabling, or topology.

In the highly unlikely event that you have a faulty switch, can always swap them to verify. If switch has any kind of green, power saving feature, DISABLE it.