I bought someone a Chromecast (current generation, non-4K). I help setup the Chromecast on the Moto Z2 Force. Installed Google Home, add device, discovered, added to same Wi-FI as phone. Everything seems to setup fine. But as soon as it finished setup, I click on the Chromecast device within Google Home, it just says "not available". I cannot cast from the Z2 at all.
On the other hand, on my LG V20, which does not even have Google Home, can see the Chromecast and I can even mirror my phone on to the Chromecast.
How do I troubleshoot this? The Wi-Fi network is not a guest Wi-Fi. Meaning L2/L3 broadcast / discovery should work.