I'm using Firefox 42.0 as my browser, FireFTP 2.0.24.1-signed as my FTP server. I keep getting error 451: "Append/Restart not permitted, try again" while I'm loading files onto FTP. This interrupts the transfer and results in a damaged file that cannot be used. A website I consulted (SmartFTP) said the cause is "FTP server denies clients to restart/resume an interrupted transfer" and the solution is "enable restarts/resumes of uploads and downloads on the server side". How do I fix this? I don't see any settings on my side that affect this.