Earlier quoted context omitted.
Oh no, I was trying different bits of routing trickery. I'm pretty sure if I sat down and gave it a solid 3 hours straight of methodical effort, that I'd have figured it out once and for all. Instead, I would have 5-10 minutes total per attempt, try something , see if it worked or didn't, then the next time I tried the Chromecast (possibly weeks later), it wouldn't always be repeatable. I also had the Casts being pow…
Did you block Google's DNS IPs? That will break Chromecast in strange ways.
All of this hardcoded DNS server BS in iot devices is a pain.