JFYI the required ports are below
The default ports are:
Port Type Description
7777 UDP/IP (Game Port)
7778 UDP/IP (Query Port; game port + 1)
7787 UDP/IP (GameSpy Query Port; game port + 10)
28902 TCP/IP (Allows your Server to Connect to the UT2004 Master Server Browser)
xxxx TCP/IP (Port set via ListenPort that your WebAdmin will run on)
Also make sure you set the following to True
Find the [IpDrv.MasterServerUplink] part in your server's ini file, and modify the following value: ServerBehindNAT=True
If you are unable to browse webadmin using the external IP address of your server, but accessing the webadmin from inside your LAN works, then the following may help you:
Find the [UWeb.WebServer] in your server's .ini file, and modify the following value (where x.x.x.x is your public internet IP address ):
ServerName=x.x.x.x
Also, please remember due to the way NAT works, any computer within your local NAT network will have to connect and view your server (via the server browser) via the LAN IP else you will have problem's connecting and get N/A for the server details. Anyone outside your network (Internet) should see your server fine now as long as the ports are opened.