DiskStation DS420+

i ran into this with my ds420+. synology is super picky about ram. ecc sticks usually just won't boot or throw errors. you're better off getting a non-ecc crucial or timetec module - they're cheap and work. i grabbed Crucial 4GB DDR4 for mine and it's been solid for two years.

As ppl have said already, it depends on if your playback device supports the codecs used in the media for direct playback (no transcoding), or if you'll have enough bandwidth in the network to even do direct playback, or if you'll transcode it in case some codecs are unsupported. the Synology Beesta