And this sucks if you're using the ethernet adapter.

TL;DR: if your Chromecast is in Android Recovery mode, unplug the ethernet connection or it will take your whole network down.

Today my Chromecast with Google TV got stuck on the boot screen. I unplugged the power and plugged it back in only to be greeted with the "Can't load Android system. Your data may be corrupt." screen. Ugh. I trued unplugging it and plugging it back in one more time, but same result. I had other stuff going on, so I just turned off the TV and left it for later.

A bit later, people in the house start complaining that the wifi is down. That's a rare occurrence, but sure enough, my phone can't connect. I restart my router and access point, but no joy, and now even my hardwired machines can't connect.

Time to dive into the router (it's an EdgeRouter, so that means a serial cable and some VyOS CLI fun). Everything looks fine, but for some reason DHCP isn't working. I can see clients making DHCP requests and the router is responding, but nothing is taking. I spend a couple hours trying everything I can think of. Finally I just give up and restore a backup of the configuration that I knew was good. _Still_ nothing works.

And then it dawns on me. I walk over to the Chromecast and unplug the USB cable. Everything starts reconnecting.

It looks like the Chromecast in Android Recovery mode runs a DHCP server on whatever network interface is connected. This makes total sense for diagnostics on a wifi connection, but just wrecks your network if you're using the ethernet adapter like I am.

Hopefully this post will save someone a couple hours of their life if they run into the same situation.