FTP issues

[KCaldwell]

I am trying to setup either the Network Audio Player app or Soumi on my phone in order to access my music on my Linkstation 420.  I have a static ip address set up for my Linkstation.  I have forwarded port 9000 to the Linkstation's IP Address on my Verizon Fios router.  Doing that allowed me to use the Buffalo Webaccess app to access my music over the internet, but that app has no features such as creating/playing playlists, does not support FLAC files and many other file types, etc.  So I figured I would be able to set up one of these two apps to work via ftp.  However I can't figure it out.  I tried entering my external ip address into their apps and it will not connect.  I am a newbie to dealing with port forwarding but I assume I am doing something wrong with ftp port forwarding.  When I check my ports on WhatsMyIP's Server Port test, it shows port 21 as closed.  Any suggestions?  How do I access my linkstation's shared folders via ftp from outside my LAN?  What is the host name or path that I need to use?

[CV_Frank]

An easy way to see if it is the firewall on your router blocking traffic (which it most likely is) is to add your NAS box to the DMZ Host inside your routers settings

Can you please post what type of router you have?

[KCaldwell]

Its a Verizon FIOS G1100. 

What does adding my NAS to the DMZ Host show me?  What do I do after I add it?  I see that is exposes my NAS to the internet so I want to make sure I know what I am looking for prior to changing the settings. 

Thanks for the help.