We have upgraded to WinSCP 5.5.3 and are now unable to connect to remote servers where the connecting client does not have a default gateway (but does have a static route to the destination server).
When connecting, it does request authentication - which works fine, but when that is finished it seems to "loose" connectivity with the remote server and gives an error message: "Transfer channel can't be opened. Reason: A socket operation was attempted to an unreachable host. Could not retrieve directory listing." Clicking Ok loads the main WinSCP folder screen but immediately "Timeout detected" is presented.
This seems to work fine with SFTP but with FTP or FTPS this does not appear to work correctly as above.
The server in question we are using is FTPS with Explicit TLS enabled.
To put things into context, we are a financial company and lock connectivity on our network down as much a possible, which is why we do not have default gateways on our PCs and only use static routes.