That's the reason why I can't connect. See SFTP_DO_2.png.
btw: also the tab names are not useful. If I have (and I have!) more connections via a tunnel I'm not able to make a difference. It would be good to use the "site name" as tab name. Also add the port number to like "FTP://localhost:3001".
I've also found out the a file call PUTTY.RND will be created in the root of my home drive (in our company). Not good. See screen shot SFTP_DO_3.png.
The FTP log can be found in screen shot SFTP_DO_4.png.
Any idea how it could work? If not, I hope DO will support it soon.
Security is more & more important. Currently I can't use DO anymore for FTP. .