Give me the lecture, what do I put in /etc/hosts? How does this prevent AT&T fucking with me? How do I make this work on all my machines to prevent this issue? Like my smart TV?
Why does your smart TV need to talk to internal hosts? If so, is it terrible to just use the IP? Or use zeroconf/bonjour which was developed specifically so normies would not have to deal with internal DNS.
Your ISP router may implement DNS proxy or more likely doesn't do any name resolution at all; or their embedded DHCP server just passes the ISP DNS IPs to the devices and the one you get is dependent on if you turned on their privacy thing. In which case you don't have internal DNS and the fact that it worked at some point in the past was coincidental and due to some fallback mechanism.
The shitty-equipment issue is not unique to ATT.
The best solution is to do what others suggest; place the ATT gateway in bridge mode and get your own router that runs OpenWRT; you can program your own local hostnames using the web GUI without touching the hosts file or knowing how DNS works, and everything should just work.
