I hope you all will be fine and in good health. Sorry for not introducing myself first and getting directly to the point. *Time is always on the run*....
I am a network administrator and I provide internet service to users in my area. I'm providing them access through a ISA Server (ISA Server 2004) which is installed over Windows 2003 Server.
Now, the issue, Scenario-1....
I have been having a weird issue with GameRanger. I can start GameRanger and log in to it's lobby where I can see various servers of different games but when I try to connect to any server or host my own server, it says that I'm behind a symmetric NAT router (Which I think is my ISA server), due to which I cannot see the servers (in-game) which my friends have hosted (The server list in the game remain empty). They can see each others server but I can't find their server because of this problem. When I looked at GameRanger own support it said that I need to port forward 16000 (UDP).
Now, I want to tell you that I don't have any port restrictions in place. All ports are opened. To solve the problem, I have even placed a separate firewall policy for allowing port 16000 UDP to be forwarded but it was to no use. I still cannot view my friends server and they cannot join mine even when I host it. I've currently removed the policy for allowing port 16000 because it didn't solved the problem. My guess is that I'm not configuring it right somehow and need able assistance in this regard.
I said that I do not have any port restrictions in place because I can view internet servers of counter strike (LeoNet, Fariya etc) and I can even play games through Garena (Such as HAWX). If there were any port restrictions in place, I could've not be able to play games online at all.
When I disconnect my ISP LAN cable from the ISA server and connect it directly to my PC the problem no longer persist. I can join them and they can join my server. But as soon as I plug it back to the Server machine I start getting this problem again.
I don't have any ISP router which is providing internet access to my ISA server. I have a CIR based internet connection and my ISP provided me a Fiber to LAN media converter only. Which is connected to one LAN interface in the server. The other LAN interface of the server is connected to a normal 8 port Ethernet switch, which is providing internet facility to the users.
To give you a clear picture of the problem I'm attaching an image for better understanding.
Any step by step guide will be HIGHLY appreciated