Protocols can be confusing, but Duplicati supports SFTP over SSH not SCP over SSH.
Pricing page says SFTP is unavailable at the 1 TB level (starts at 5 TB). This limitation also seems to impact rclone. Duplicati needs the ability to list and delete files, and it’s not clear that SCP has a defined way to do so.
EDIT: Ignore 5 TB talk. Pricing at 1 TB that used to say
SSH/SCP is now updated to
Another protocol option starting at 5 TB level might be FTP with its encrypted
FTPS form. Is that there? Original unencrypted FTP over the Internet is insecure. Duplicati data may be encrypted, but login isn’t.
I suspect SFTP will work better in Duplicati than FTPS (if you have it) but I haven’t performance-tested.
Some people might not be bothered by the 5 TB effective minimum, but I mention it in case some are…
EDIT: Pricing page fixed per the post below, and detailed on EDIT above. Thanks for updating that page.