If you’re struggling to Chromecast…

…just double one of these (I think I did network streams) and you should get a pop up from defender to allow connections. All the guides were talking about a non-existent scan button and shenanigans with turning off the firewall. Not sure why this isn't stated anywhere either way this worked immediately and it found my Chromecast. [Playback > Renderer ¦ if you don't know where to look]