How to make chromecast work across two OpenWrt router?

[sampson]

I have two OpenWrt router that clients can access each other.

I have a ChromeCast Ultra connect to the wifi of Router1. How to make clients of Router2 able to discover and casting to the ChromeCast Ultra?

[frollic]

Chromecast on kids network

Chromecast relies on multicast DNS, which uses broadcast packets which are not forwarded between networks by routers. You need a dedicated relay service such as avahi running on the router. I have not set this up myself, but you should be able to find information by searching these forums and the web generally.