I could not stream any media from my computer through Plex and Chromecast – it was constantly buffering. After playing with all the settings in the Plex server (there’s not much to fiddle with in Chromecast), I found that nothing improved the constant buffering. Then I tried this:
Make sure your WiFi router is set to a band frequency that isn’t packed. Mine was set as default by Telus at frequency 11, which was always packed with traffic from other WiFi routers in my area. See below. I set it to 4, which constantly had the lowest amount of traffic.
(You can download a WiFi analyzer app on Android and iCrap)
The change was amazing, no buffering and instant access to the Plex folders. It competes, but not nearly as much. Setting the frequency to auto detect was okay, but setting it to 4 was the best…for now.