Question for people who understand networking and data communication (because I know a few of you get hard-ons for unshielded RJ45 connectors). I just moved into my new place, and I was borrowing the wi-fi until a tech comes to set up my own service. However, getting wifi to my desktop it like getting a cat into a carrier, no matter what kind of card or dongle I have stuck into the ports, so I thought of hooking the cable TV cable into my modem and... It works.

However, I read online that it's impossible to have two modems on the same connection. Yet... Here we are. Could I have inadventently booted the family upstairs off their modem? Am I doing something illegal? Could service be tied to my modem and not to my old apartment? Could the previous tenants have had internet that's still active? How do I find out? D: I need my internet, but I need it to be kosher.