I had this question after viewing Allow Local User to Log On FTP
More specifically, now that works and local user can log on, the developer has written a program that does several things. New problem is that when the program is running on a dev box it works, but when it runs on the server that is hosting FTP, it fails. Server connects and then fails with "connection closed by remote host".
I tried this myself running a command prompt on the server. Same problem, connection closes as soon as it opens. The odd thing is I am sure I tried this before when working on my previous question.
The only thing that I found works is if you log on using the IP address. If you log on by the server name (short or FQDN) or localmachine, it fails. However the goal is to make the program portable, so specifying the IP address is not the best way to do it.