Hi Stef,
Yeah, this can be a problem because when the administrator logs in, he's connecting with a local IP address that the other players can't connect to. This is especially a problem when the FSHost server and the local player are on different machines on the same local network. If you have a router or firewall, you have to forward the ports to go to the FSHost machine, and then the data isn't making it to the admin's machine. One thing you might try is the DXport program at
www.puffinsoft.com. This program lets you change which ports are used by DirectPlay, so you can do things like assign the range from 2300 to 2309 to one machine, and 2310 to 2319 to another machine, rather than letting DirectPlay randomly pick which ports it wants to use. When this is running, you can then forward just those ports to each of the two machines, so you don't have to forward all of them to only one machine.
Hope this helps,
Russell