Here is the solution you are looking for: https://support.plex.tv/articles/200890058-authentication-for-local-network-access/
Basically you can add IPs (such as your local domain) to bypass authentication. The only caveat is that you must be online when you set this. IE: You can't do it during an outage.
Fucking Lemmy.world is hot garbage. They're down every day and are constantly defederating with any instance that doesn't fit their narrow, sanitized world views. It's also one of the most recommended Lemmy's with more new users going there than anywhere else. I think it incredibly damaging in the long run to have 50% of active users on this platform to be centralized on one domain. Especially if this domain makes as many boneheaded decisions as lemmy.world