FTPSync: File size limits when transferring large files

FTPSync by itself does not impose limits on file size to be transferred. However, due to firewalls prematurely timing out FTP sessions, it’s possible that your specific setup may impose a file size limit, which may be as low as several MB and as high as several GB. Usual symptoms are:

While most FTP clients include various workarounds to combat this problem, there was non in FTPSync so far. The first one, a TCP/IP Keep Alive on control connection has been added in FTPSync 2.8c. I will continue to investigate further possibilities and implement them in FTPSync in future versions.