Hi,
I just instal plex to cast film with my google chromecast.
I installed a server, dowload my films.
When I play a movie on my cumputer it’s ok, but when I go for start to cast (on my tv) an error appear :
“Playback error
The server " *** Server” has no valid connection for broadcasting. Verify that the server is selected in the server settings."
Can you help me? Thanks guys 
(P.S. : Sry for my english)
