Try checking if your FTP application (FTP client) settings is set to PASV mode.

Example of settings
For FFFTP (Windows)

1. Start FFFTP.
2. In [Host List], select Asahi Net settings and click [Change Settings].
3. Select [Extend] tab and place a check mark next to [Use PASV] mode.
4. Click [OK] and close.

For Fetch 3.0 (Macintosh)

1. Start Fetch.
2. In [Customize], open setting dialog from [Preferences].
3. In [Firewall], place a check next to [Use passive mode transfers (PASV)].
4. Click [OK] to save settings.