Chromecast on non-RFC1918
From OISecWiki
I ran into a problem with casting from Chrome to a Chromecast, android phones would work just fine, but Chrome would refuse to cast. The cast icon was available but it would not find a chromecast to cast to. After some research it seems that Chrome stopped working for quite some people after Chrome 63.
Apparently there has been a new chrome flag that disables casting to non-RFC1918 IP addresses. To enable the old behaviour go to:
chrome://flags/#media-router-cast-allow-all-ips
And enable it. After a Chrome restart your problems are fixed.