Hello @ghyduart,
I have split your post as to better assist here. Can you please provide an overview of your network and core using this thread as a guide?
Specifically, please let me know your Router model/manufacturer and the mode/manufacturer for any switches/range extenders/powerline adapters/ect.
How is your Core connected to the networking gear? Are you using Ethernet or WiFi? How is your Chromecast Audio connected, do you by any chance have the Ethernet adapter for it?
Thanks,
Noris