When casting to Chromecast devices by default Symfonium generate URLs based on your provider configuration so that Chromecast can directly stream the media from the server.
DNS issues
This can cause issues in some cases if you use complex DNS infrastructure as Chromecast devices hard code their DNS and will ignore any configuration send by your DHCP servers. Be sure to use solutions accessible from Google servers. Else see below to proxy the media.
Proxy media
If you use VPNs or other solutions and only your phone have access to your server, you need to enable proxy mode so that the media goes from your server to the phone then from the phone to your Chromecast.
In the cast bottom sheet press the setting button near your Chromecast device
Then enable the option Proxy via Symfonium
