I have a QNAP TS-131 NAS and I connected with WinSCP to it. Whenever I start a copy or move operation, after 15 seconds I get the error "Host is not communicating for more than 15 seconds." . Like it's suggested, I disabled the option "Optimize connection buffer size." , but it made no difference. However, if I don't abord the operation, the file transfer (move or copy) is done successfully, and then the message disappears and winscp continues to work normally. Anybody know what I can do about this error ? Thank you.