That means your server is now unclaimed.
You need to claim it again: New Claiming Requirement for Windows
Did you web browser ask you about permission for the website 127.0.0.1 to access the local network? You need to allow that. The same applies to app.plex.tv https://forums.plex.tv/t/important-note-about-the-plex-web-app-local-network-access/933264/1
Do also keep in mind that you should use a web browser for the claiming process which isn’t designed to impede websites (Brave, et al.)
