I have just moved into a new home and there appear to be ethernet lines running to several rooms, all converging in a wiring box. However, I can't figure out how to make this thing work properly. Here's how it's set up.
The blue cables I'm holding in this picture apparently run to the other rooms of the house. The yellow cable goes to my WRT54G router. A cable modem is plugged into the router. Wireless networking is functioning properly.
If I plug my laptop directly into this box, and disable wireless networking, I can reach the router from the laptop, and the light for the yellow cable going into the router turns on. However, if I plug any of the blue cables into any of the ports on this box, the laptop loses connectivity and the link light on the router turns off, as though the router were not plugged into the box at all. Why does this happen?
The cables are cat 3e. There is an alarm system, but it is not active, and I don't think it's actually connected to the box at all. The top-left port is marked "RJ31X Line Intercept", and there is a jumper that can be plugged in there, but it doesn't seem to matter whether it is or is not plugged in.
How do I correctly use this box?