Orreven

FTB pack, Direwolf20 1.6.4 pack in specific, the ready-to-launch server files they let you DL in a .zip from their site. I couldn't get the standard forge server.jar to work so I used the server.jar from that download in the same folder and it worked fine.

Ok, do you have any fix for when we did use the proper download, and the Direwolf20 server.jar works in the same folder as the one where the standard forge server.jar does not?

Everything the above said.