Synology Hyperbackup to OMV Rsync SSH Fail

I am trying to create a backup job using rsync from a Synology server to an OpenMediaVault server. I have everything set up, I connect correctly but without encryption (port 873). If I try to activate SSH encryption (port 22) I get a connection error. I have verified that if instead of putting that user I put the root user it does connect me through SSH, but obviously I don't want to do it with root. Is there some option that I have to activate and I miss? From the terminal I can connect with that user through SSH, and obviously it has read and write permissions on the folder to be synchronized, ssh permissions and the rsync task is launched with its user and group. It is also within the _ssh group.