I’m having the same issue - but with my own NAS which runs a mix of Debian testing and OpenMediaVault. I’ve set up a backup using borgbackup, which is working fine, but I wanted to try Duplicati just for fun (well actually it supports Amazon Drive out of the box, which is what I’m looking for).
I have a ‘backup’ user on my NAS who has a home directory residing on /export/NAS/Backup - borgbackup is just putting its files in a directory relative to the home directory of that user.
If I try doing the same thing with Duplicati I get the ‘Failed to connect: No such file’ error. Just to be clear, I’m using SSH file transfer (SFTP).
I was trying with ‘duplicati/pcname’ or ‘/duplicati/pcname’ or ‘~/duplicati/pcname’ or ‘./duplicati/pcname’
I also tried connecting with FileZilla using SFTP which works fine, I can access the folder, create stuff, delete stuff. Just like borgbackup does as well.
I also created the directory and tried again with duplicati - to no avail. If I leave the directory empty it says okay but ends up with a permission error. Troubleshooting is hard because I have no idea where Duplicati is trying to go.
Solution: This still seems like a bug in Duplicati:
into the folder.
I find that rather strange and completely counter intuitive compared to how every other tool at my disposal handles this.