While the ‘global’ calendar I’m not 100% sure on (sharing a calendar with all users I guess does it), synology does everything else. I’ve had my folks slowly migrate to my server over the last couple years, and we haven’t done calendars yet (hence my uncertainty) we have files, photos, I have todo and calendar, along with plex and others. It has to just work and be inexpensive, and this nas checks both boxes (hardware notwithstanding; no subscription costs).