That error is coming from your FTP server, which basically means it will only connect to your external IP address and not your internal LAN address.
Please check to see if you are on Passive or Active connection in your profile? Go to:
Modify > Expert > FTP > Firewall
Is the option "Passive (may be required if using firewall)" checked or unchecked?
If it's unchecked then you are using an Active connection, if checked then Passive.
Make sure it's checked.
Please check to see if you are on Passive or Active connection in your profile? Go to:
Modify > Expert > FTP > Firewall
Is the option "Passive (may be required if using firewall)" checked or unchecked?
If it's unchecked then you are using an Active connection, if checked then Passive.
Make sure it's checked.