Registering Borg public key onto Synology NAS

Dear all,

I’m currently trying to configure Borg Backup (fresh AIO v32 instance) to push backups to a remote Synology NAS.

I’ve created a dedicated “borg” account with the NAS, checked that SSH was activated, created the .ssh directory within the borg home dir, created the authorized_keys file and copied the public key returned by AIO interface. All access rights are OK.

I’ve then set the ssh://borg@mysynology/volume1/homes/borg/backup destination path and triggered a first backup but Borg fails to authenticate against the NAS, which returns “User [borg] from [Nextcloud-IP] failed to log in via [SSH] due to authorization failure.”

Unfortunately, if I can easily ssh into the ‘borg’ account using its password (using MobaXterm/Win11), I just can’t check that the public key is properly accepted as I don’t have the private key at hand on my machine…

Any clue?

Thanks in advance for any help!