You might also try running Plex via docker on DSM 7 Preview. I don’t know anyone that’s tried it yet, but my suspicion is it’d work as well as on docker on DSM 6 (which means you’ll loose hardware transcoding without jumping through hoops). If you’ve already updated to the DSM preview though you’ve got nothing to loose. There is no published timeline, but DSM betas are typically pretty long and my guess is DSM 7 RC and Plex support for it is 6 months away.
This might get your started, but there are dozens of other good threads and pages. Synology Plex and Docker
