I have just gotten this to work. Here is what I did. SSH into server perform these commands, no quotes "modprobe i915" "chmod -R 777 /dev/dri"   modify the docker container for plex and show advanced Extra Parameters (No Quotes) "--device=/dev/dri:/dev/dri"   I did enable "Privileged" however some folks stated earlier that wasn't required. Who cares it's working now!