If you go looking for a pre-made Network Attached Storage server, there are several that have Plex as a free add-on package. Just sourcing video to capable devices should not be an issue.
But, if you have "less capable devices", not able to take the full DV stream, it would be best to verify that the NAS has hardware capable of supporting Plex transcoding video. Synology servers can do it, but, even with Intel QSV on board, providing more than one transcoded video stream may not work out so well.