Comment by pseudohadamard

My mother moved into a retirement village a while back and I was pleasantly surprised to find Ethernet jacks in every room, in some cases more than one. There was no patch panel or anything which was a bit odd, maybe hidden in a service cupboard, but initially I just needed to get a connection from the router to the bedroom and established that these two jacks there were connected. Hooked it up, nothing worked no matter what I did.

On the next visit, with diagnostic gear to look at the wiring map, I found out that the Ethernet jacks were wired up for phone lines. Some genius had decided to run Ethernet to every room, with RJ45 wall sockets, but wired it up for phone lines, so it was simultaneously unusable for either phones or networking.