In a recent Firefox browser update, my ability to reference my home router by name via the Windows HOSTS file stopped. I can ping the router by name from a CMD window just fine but keying the name into Firefox now fails. Images show the two forms of failure - a 500 Error when DNS over HTTPS is enabled; a 'having problems' error with suggestion of www..com alternative when DNS over HTTPS is disabled. Neither is the least bit helpful.

I can't imagine what changed and I can't find a prior support response that gives any clear ideas.