This post is to explain my setup in case someone wants to do something similar.
I have three servers in three different locations that sync between each other. Each location is the home of a family member and each location has additional devices (phones, laptops, and desktops) that sync with the server at that location.
If a phone dies or if a server dies then all you need to do is replace it and set up the sync to get the files onto that new replacement device/server.
Each server also has some shares for common files and media like music and videos. The shares are used because the other devices don’t have the space that the servers do. Certain files like pictures from the phones and personal documents from the laptops and desktops are synchronized with syncthing but other larger files would be accessed using the shares.
The trick to this is the folder setup on the servers. Before you jump into things you should think about how people will get at the files they need or want to have backed up. In my case each person has their own personal folder. These personal folders have tight security. Access is through syncthing only. Family/shared data like pictures or family documents sit in a folder/share with security allowing family to get at those files. Media like music and videos sit in a Media folder/share which has general access.
Once last thing is that there’s a backup server sitting at one of the locations. Syncthing syncs to this server and then that backup server creates periodic snapshots of the synchronized data. This allows for recovery of files (like accidental changes or deletion, especially ransomware).