I use an rsync job to do it. Rsync by default uses the files metadata to determine if the file has changed or not and updates based on that. You can opt to use checksums instead if you’d rather. IIRC, you can do it with a Synology task, or just do it yourself on the command line. Ive got a Jenkins setup to run it so i can gather the logs and not have to remember the command all the time (and i use it for other periodic jobs as well), but its pretty straightforward on its own.