Chromecast control from home assistant without internet?

I am using Node Red and the cast v2 node to initiate music play on a samsung sound bar. Works fine when the internet is connected, but for some reason, the Samsung sound bar and a Nest Audio device are unavailable when the internet is out.

Is this normal behaviour? Any way around this? Can i use any method to get my local jellyfin music playing on my local chromecast devices without it connecting to the internet first?

Thanks for any help and ideas

Chromecast relies on the internet to work. Apps send a message to the Chromecast using a web socket and ask it to load an application by the apps ID, which the Chromecast looks up at Google to translate a ID to an actual web resource on the internet. The Chromecast is essentially a cut down glorified Chrome web browser, it cannot do anything with an internet connection.