This is a result of one of three things (in general):
1. A local Firewall or Anti-Virus software is severing the connection. To check this, TEMPORARILY deactivate your firewall / Anti-Virus software and try again. (Make sure to check your local windows firewall if you are running windows.) If your Anti-Virus software was the cause you will want to enable your ftp software as try again. For assistance on this contact your Anti-Virus software provider
2) Your connection through your ISP is being cut off. To check this you can contact your ISP and have them conduct an FTP test.
3) The server is not responding or having issues. You may contact us to see if this is the case.
Other than that, the issues will vary depending on the local machine and environment.