Using rsync to keep folders in sync on a Synology Diskstation NAS

http://www.markwilson.co.uk/blog/2016/09/using-rsync-to-keep-folders-in-sync-on-a-synology-diskstation-nas.htm

https://zarino.co.uk/post/synology-rsync-backup/

https://forum.synology.com/enu/viewtopic.php?p=374226&sid=6aff48d543256d5d5515702af36acf35#p374226

https://forum.synology.com/enu/viewtopic.php?f=116&t=98325&p=370460#p370460