Hmm, you saying you don’t have a router, I wonder how you are connected, is it a dial up connection?
Then I would guess this could be the problem, but I’m not a router and net-guru. Earlier a had a dial up too, but forgotten all about it. A dial up is - lets say – one line and can not handle multiple connections, but should be configurable to service to PC’s for example , but I’ve forgotten how to manage this. I can’t give more advice on this matter – sorry :(