Enable IGMP snooping - on ✅ ( Networks section, works only if you have a UniFi Switch) - Networks need to manage broadcast and multicast traffic because otherwise it eventually degrades the network health.

Ubiquiti have a support article on UniFi Best Practices for Managing Chromecast/Google Home which goes through how to configure a UniFi network so you can cast to Chromecast devices on a separate VLAN. It might work for you if you have a similar setup, though it won’t work on a UniFi Dream Machine (UDM) for reasons described below. My network is built around a UniFi Security Gateway (USG3), a UniFi US-8–60W Switch, UAP-AC-Pro Access Points, with the controller running on a first generation UniFi Cloud Key, all with latest stable release software as of February 2021. Hopefully it might save someone else some time.

I figured this out after a lot of searching and finding inconsistent answers.

I wanted to have the protection of putting Chromecast devices on this network, and still be able to cast to them from devices on the trusted and guest networks.

I have a separate “Internet of Things” network to limit the potential impacts from untrusted devices around the house. Google Chromecast on a separate VLAN with UniFi Security Gateway

Google chrome cast ap