I connect regularly to the server at work (where they allow only SFTP connections, not FTP) from home in order to transfer files .
For approximately one year, using the successive latest version of WinSCP, I have been experiencing systematic and recursive disconnection when tranferring files. I need to reconnect every 15 seconds to achieve the transfer.
I have first thought it was a server issue but after inquiry it appears it was not.
I then tried other file transfer softwares enabling SFTP connections (essentially FireFTP and Fillezilla) with which I have had no problem at all: the transfer is fine and fast (no disconnections).
Therfore, it may be possible that this is a WinSCP issue.
I am ready to furnsih other details to help you if you need.