I get the same issues as most people on the latest version (1.13.5), but I also get dropouts when I set up the docker container but downgrade to 1.13.2. Seems to play for about 10 or 15 minutes then stops. It seems better, slightly, on the older version, but not a complete fix.
I'm planning to switch to Emby in the meantime and try Plex again in a few weeks to see if this is fixed.