Pull backup from client to OMV server, what to use?

I have a Raspberry Pi running 24/7 which hosts my Nextcloud instance. Data are stored on a 500GB hard disk attached via USB. I'd like to perform regular (incremental) backups of that disk as well as the Nextcloud database and folder to my OMV server. Unfortunately, I still can't WoL the server so the obvious method that the RPi wakes up the server currently isn't available.
However, the RPi is running 24/7 so if the OMV server could just pull a backup each time I switch it on manually, that would probably already be fine for the time being. Which software would you recommend for this job? I read about UrBackup, is that a good choice?