I have a DS220+ and I use it pretty heavily as a local plex server for music and videos. Actually barely use it as a backup solution (Time Machine kinda sucks, need to find a better solution for backing up my mac to it)
From my experience it does work, although I never experienced it, say, using a Time Capsule or similar?
'Time Machine detected that your backups on “xyz Time Machine Folder” can not be reliably restored. Time Machine must erase your existing backup history and start a new backup to correct this.'