seconding rsync and syncthing. the server could expose an smb or nfs share, the client could mount it, and then sync to that mount. rsync over ssh also works,

seconding rsync and syncthing. the server could expose an smb or nfs share, the client could mount it, and then sync to that mount. rsync over ssh also works, if you do not want to run smb/nfs. this is also a cool tool https://rclone.org/ https://rclone.org/