network connection Pop-Up message; LAN disconnected/connected continuously pops up

[yeetmopedfoahn]

I have a 55UK6400PLF and it was working fine since I bought it. Now I moved to my girlfriends house and now LAN and WiFi won't work. It won't even connect to the WiFi it just comes up an Error message that it wasn't able to connect to the network and that I should check everything and try it again. Not the biggest problem because I would like to use a Ethernet cable. When I plug the Ethernet cable in my TV, a pop-up comes up which says that it's connected to the network via network cable and immediately afterwards it says "lan not connected". This continous until I  remove the cable. I made an factory reset on the TV and on my Router. Still doesn't work. The WiFi and LAN works fine for everyone but not for my TV. Somebody got a quick solution for that?