I have a FTP serverinside my network with a fixed private ip address and a static public IP address. The server is set up in a DMZ and I am running BlackIce. I have opened ports 20 and 21 and for PASV I have ports 50000-500049 open. Connections to the server in active and passive mode from outside my network are just fine.
Connections from all but two PC's inside my network will connect in active and passive mode but when the LIST command is issued error 425 comes up. Some have recommened making sure the MTU size is the same for all the PC's and all are set to 1300.
I am using the filezilla server and the filezilla client.