Help with home connection

Hi everyone, first time posting here. I just moved in a SATO apartment and they said I have internet connection in the rent so I went to telia website, bought a router, connected it but no web connection. I called Telia Helppi but they said that I need to make the right connection in the box on the wall (see photo) but the could not guide me at all and they said "try everything". Do any of you know how to do the connections? I don't want to call again and get pissed off about this, I have better thongs to do.