Nice, I’ll try to test it out today or tomorrow. Thanks!
Based on good earlier testing, I did some more research, and gave SSH.NET a theory of failure here, piggybacking on the existing GitHub issue. Theory still sounds good, but their confirm would be nice.
Can you test Control Panel → Server Management → Edit advanced settings → SSH algorithms → Signature, and see if unchecking all the ecdsa ones gets your Test connection and backup going?
@Rob_Canada can test similar if storage device is configurable. Some might need to know OpenSSH configuration, where I think @drwtsn32 knows more than I do (and doublecheck Bitvise above please).
Sorry for the delay in my response. I already implemented the workaround provided by @drwtsn32 earlier (removing the ECDSA host key on the Bitvise SSH Server), and I can confirm this works (now defaults to RSA host key).
Great work on tackling the root cause everyone. I assume the merge request will take some time to make it to the beta, but the workaround works fine, of course. Thanks again 
2 Likes
Release: 2.0.6.2 (experimental) 2021-05-29 is out with what is believed to be a workaround for the mono bug that broke SSH.NET that broke Duplicati. ECDSA host keys will not be used in mono until supported.
@Rob_Canada and @ghysler (and any others who saw this) are invited to remove workarounds from servers, and test it out. It should be safe to stay on, as it has only two changes from 2.0.6.1 Beta release, however you can set the Update channel back to Beta if you prefer to avoid future Experimental releases. Experimental is currently used as last step before Beta, so this code will probably be next Beta after test.
If you generally upgrade from Duplicati autoupgrader, you can go to Settings and change Update channel from Beta to Experimental, and it should offer this upgrade. If you prefer, installing manually will also work.
For best testing, please go to the Destination screen Advanced options, delete any ssh-fingerprint option, then use the Test connection button to accept a new one. Remember to go to final screen 5, to save it.
1 Like
I just updated to the 2.0.6.2 experimental version for the Synology, and it now works great!
Indeed, I again would like to thank everybody for such a great effort. I will stay on the Beta path but always look forward to the latest and greatest. On the rare occasion that something breaks, it’s fantastic to see such a vibrant community.
3 Likes