Users have trouble downloading large files via internet access

I think I have seen something posted here regarding disconnection of the FTP connection when remote users get disconnected during an FTP download connetion accessing the Sharespace over the internet.  I could not find it so I am posting here as this is the problem I am having. I am not certain where the disconnection is taking place.  Users have reported this problem using a number of different FTP clients. 

The users are remote and accessing the Sharespace via the internet.  Files being accessed are in the download directory.  It has nothing to do with the Twonky Media Server unless Townky controls FTP. 

Would appreciate any input.

Thanks

How are you forwarding your ports? If your router creates logs of this behavior could you post them so we can see whats going on?