Hosting multiplayer games working one day then not again?

[Bitterestmite3]

hi. i recently downloaded 3.1.1.
on the same day i hosted a multiplayer game with no problem other than lan.
now ever time i try to host another game i get "connection timed out make sure port 2100 is open." but i never changed the settings from when i hosted the first game. what should i do?

[vexed]

Would need to see your WZ logs to diagnose, using --debug=net