Had stuttering and buffering problems.
Added Chromecast.xml (see below) to
Plex/Library/Application Support/Plex Media Server/Profiles
fixed almost every problem
Setup:
Synology Diskstation
Plex Media Server
Chromecast
File to download here: http://www.mediafire.com/view/ly674y942dpedhf/Chromecast.xml
Don't forget to restart your Plex Media Server!
