Getting error "app.plex.tv is unable to connect to "<my network>" securely

Plex Media Server Desktops & Laptops
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1

Server Version#:macOS 15.6.1
Player Version#:4.152.0
<If providing server logs please do NOT turn on verbose logging, only debug logging should be enabled>

2

Maybe this helps?
https://support.plex.tv/articles/206225077-how-to-use-secure-server-connections/