Either sftp/ssh with key-only logins (ie. no passwords), or Syncthing (depending on the volume of data, rate of changes, speed and costs of your network transits)

I now keep my primary 'work' and 'private' collections (10-30g each) and a large shared set (350g) synced across desktop & laptop, and also 3 off-site archive servers, using Syncthing. This includes a literal satellite connection for one site.

[0] https://syncthing.net/