Network Help Please!

Hello all, I have question that maybe one of you could help with.

Here at our office we have Cable internet. It comes into the office, into a giant switch and then is routed to all the Cat5 connections (computers) in the office.

Well we had someone new start and there isn’t an extra cat5 connection in their office. So what I did was buy a router. I plugged it in, fired up the computers and the internet worked great.

Problem is, neither computer is now on our network. When I check the workgroup from either of their computers it only lists the two of them and not the rest of the office.

I am wondering 2 things…

  1. Is this easy to fix, and if so - how? Keep in mind we have a dynamic IP if that means anything to you.

  2. Is there something else I could buy instead of a router that would be less hassle? Maybe a Hub?

Thanks for the help guys/gals, I really appreciate it!