You say you cannot authenticate, but you say that the port does seem to be getting redirected. Ok what happens? Do you get an authentication prompt?
Have you tried from the command line?
C:\>ftp
ftp> open
Connected to ************.net.
220-FTP Server Ready.
220-Guest logins are not allowed here. You must login with your assigned
220-username and password with your FTP client program. If you're using
220-Internet Explorer, try the "Login as..." menu option under the "File" menu,
220-or in other FTP client programs, you can try this URL:
220-
220- ftp://username@YourDomainName/
220
User (**********.net

none)): gconnect
331 User gconnect okay, need password.
Password:
230 Restricted user logged in.
ftp> ls
200 PORT command successful.
150 Opening ASCII mode data connection for /bin/ls.
What type FTP Server?
What output does the FTP client or server log you when you attempt to login via FTP?
What does the pix log say?