IMO, you would get much more of a bang-for-your-buck by building a one or two card rig with a cheap motherboard, cpu and a RX470/RX570 VGA rather than trying to use the Synology for mining. Any ATX B250 motherboard would be a good choice for up to four cards. You could also pick up a used Dell Optiplex or HP from Craigslist or Goodwill and add a card and risers for a basic cheap rig.
I already have one, however, I run a small business and am getting a NAS for that. So i was hoping to kill 2 birds with on stone kinda thing.
yeah but no one has done it and I am pretty sure it can not be done.
maybe if you have mad skills you could do hdd mining with it. but I would not know anymore then to point you to burst coin which uses hdds. the more tb the better.