[Austin]

I have not yet used 1.6 but what I am about to say about 1.5 should apply the same to 1.6


If you are behind a router using NAT, the default for most routers now, the PC running CS will have a non-routable IP address usually starting with 192. This is a non-routable IP which means it can ONLY be used on a LOCAL LAN. It will not go out of the router so the world can connect to it (at least not by initiating a connection from the outside)

For 1.5 if you start a LAN game only people on the LAN will be able to connect.
But if you start a dedicated server and you have the incoming port 27015 set to pas on to the PC running the DS then everything works fine. I ran a sever like this for a long time.

For 1.6 the port may have changed, but you MUST have some port forwarded to the game server for al of this to work.

The other thing you could do is not use the router (not a good idea these days with all the worms and viruses)