Quite FAN upgrade for Synology NAS
Synology 916+ NAS fan upgrade
Noctua NF-A9 FLX fan have been also working with
Synology DS215j NAS
Synology DE216+ II
Synology DS 713+
Synology 718+
and other Synology models like DS918+ , ds1019+ and more.
Here is how to do it https://www.ifixit.com/Guide/SYNOLOGY+DS918++:+a+complete+disassembly+in+rules/98384