Is there any progress on auto-reconnect during compare? The linked feature request (https://winscp.net/tracker/25) is marked as resolved, but it looks like the fix was implemented only for file listing. Maybe the issue should be reopened? I would really like this feature.
Comparing is mostly about listing. So that's why it's marked as resolved. Does your connection break in other situations? Please attach a full session log file showing the problem (using the latest version of WinSCP).
To generate the session log file, enable logging
, log in to your server and do the operation and only the operation that causes the error. Submit the log with your post as an attachment. Note that passwords and passphrases not stored in the log. You may want to remove other data you consider sensitive though, such as host names, IP addresses, account names or file names (unless they are relevant to the problem). If you do not want to post the log publicly, you can mark the attachment as private.