When you are attempting to FTP a file to us through an FTP program, by default it will use port 21. However, we use secure FTP (SFTP). Since we utilize SFTP, you will need to make sure port 22 is used instead of port 21. Many file managers will automatically switch the port to 22 when SFTP is selected, but it is a good best practice to make sure port 22 is being utilized. If you have any questions, please contact your account manager for more details.