If you are using a linksys router, follow the steps.
1. Go to your Linksys router config screen (
http://192.168.1.1).
2. Logon with whatever adminstrative ID and password you defined when you setup the router. (If you aren't sure what it is, leave the "username" area blank and type the word "admin" for password.)
3. Select "Applications and Gaming" from the main menu
4. Select "Port Triggering" from the sub-menu.
5. On this screen, make 2 entries. The first can be called "Toontown1", then specify port number 6112 in all 4 of the port fields. Check "Enable" at the end of this line. Underneath it, make another entry called "Toontown2" that specifies port 6667 in all 4 port fields, and check "Enable" for it.
6. At the bottom of this screen, press the "Save Changes" button.
7. Startup Toontown and give it a try!