So I've been l've been playing Unreal Gold and decided to start a server up so that me and my friends could play online. However, we can't seem to get a server to show up online. It's only showing up in Lan Games to those on the same local network. We've tried a couple pointers after a quick google search, but have had no luck. There are alot of guides mentioned in various forums but nearly every link seems to be dead!

Also, how do you set the difficulty in Co-Op servers? Thanks!

You have to do some port forwarding before your game will be accessbile for other people.
Refer to your router's manual on how to that or maybe your ISP might help you out.

If you know what router you have and don't have the instruction manual handy just use

http://portforward.com/

I am using a WRT54GL and I am/was in the DMZ so basically all ports are forwarded.

Not too sure then, when I want to play an online game with friends we just all load up into either game ranger if the game is supported or hamachi.