I at first ran flserver on my main 'puter. I had a hardware gateway/firewall and a software firewall. I had to make open ports in the firewalls to let DirectPlay (some M$ software) talk so FL MP and flserver would work. To check what ports you need open read some rtf/txt/html file that comes with FL and it lists the ports to open, I think 2300-2302. You can change that port (it actually only uses one) like I did but you must add a switch to flserver's command line when starting. When I moved flserver to a dedicated 'puter it was on my home network and the port already open so there should have been no problem.
Well there was. I used to run Win2K on this dedicated 'puter. But I couldn't get flserver to talk to anything, even the FL MP in the home network (LAN). I tried for three days but no joy. I switched to WinXPPro and three hours later it worked. (I will go back some day though!)
You can try troubleshooting. When you switch flserver to console view, do you see successful connection messages? flserver works. Does your FL MP find the global server and all FL servers except yours? FL MP works. In my Win2k case flserver wouldn't connect and I thought my problem was a Win2k security/permission issue. Good luck.
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{RN}Earendil
SysAdmin of Boston Freelancer server {RN}