router AX1800 does not detect cable (and can't connect to the internet)

Hi,

I finally figured out what was (probably) wrong.

I talked to the admin guy, and unfortunately, he had no clue. I tested a lot of things, including resetting the router, changing the "type", etc.

But someone working in electronical ingeneering had an idea.

(And by the way, yes, my administration, the admin-sys guy, they all know what I'm doing (maybe not all the technical details), I appreciate your concerns on that but seriously, I'm not risking my job here).

It seems that the electrical power coming from the plug on the wall is not strong enough to be "detected" by this router. I don't know exactly what the thresholds and norms are, and how devices detect them, but some devices (most of them) can detect it and, and this router can't.

I do not have the device to test the power directly, but it finally makes sense: the router says that the cable is unplugged because testing the electrical power is one way (the only way?) for a device to detect that "something" is plugged.

It explains why it worked perfectly in another building, same network but somehow the signal is better there.

It explains why most of devices could connect easily, except this one, and changing MAC address and everything in the router's configuration did not change anything.

Since I cannot magically repair/fix whatever is in these wires behind the wall, I got a simple switch, plugged it to the wall and to the router. This switch provides a signal strong enough to be detected by the router, and it works perfectly from now on. We have a couple switches lying around so nothing is wasted. Yay!

I explained my "solution" to the admin-sys guy, who went like "oh... that might explain why we have some network issues in this part of the building". I guessed I helped him understand some issues...

I'm posting this here in case it could help someone else. To test it, find a switch, plug the switch to your internet source and to your router, and try connecting.