I have read previous posts on this issue and have not been able to successfully connect using my DI-624 router. I'm hoping someone having a similar problem can assist. 2004 DOES work in MP without the router.I'm not a wiz at router port configs but I have opened 23456 and 6073 as specified on the MS web site.Other games have no trouble running through the router so I don't think it is a DirectX issue, 9.0b is in use.What I really want to do is to run an instructor station and MSFS2004 on the same LAN.Thanks for any help.

I'm no expert but I believe you need to (a) choose a different port on the host machine (from the Host Options dialog) and (:( match the port settings of the client machine with those. I know it's not much, but maybe there's a clue there.

IIRC Matt there are more than 2 ports need to be open for FS and as Tdragger suggests you may have to change the 23456 port one one PC.There is a way to run DXdiag to check if the two PCs are communicating, sorry don't know the details but MS KB may help.