GMOD port forwarding not working or?

[zeromention]

Hey guys,
I'm new to the intricacies of SRCDS so please excuse me if I make an idiotic mistake.

My gmod server refuses to work over the internet, but works fine on LAN.
Obviously, that's not surprising.
What's surprising is that rcon works, over Lan and Internet.

I also do not have a router but a "Microsoft Internet Security and Acceleration Server 2006". However I am sure I have port forwarded correctly.


If anyone can help, please PLEASE do so.

Thanks,
Zeo!