I use the Plex app on Win10. I configured my own certificate infrastructure in the Plex settings.
When I click on Servers/Edit in the Win10 app, I see several connections, all of them are grey, except for the one I configured in the server settings which points to my domain.
When I'm not signed in, I can watch a movie (for a minute) and the server notices correctly that this is a local connection. When I'm signed in and start the movie, the logs tell me that this stream is considered to originate from WAN, though I started the stream from my computer in the same subnet, one hop away from my server.
This wouldn't be that much of a problem, but I'd like to use the new features where Plex tries to remain in a configured upload bandwidth budget. Local connections do not affect this budget, but the local connections the server considers external do. Since my upload is pretty low (12MBit/s), the server even reencodes movies I try to play locally if they exceed the bandwidth budget because the server tries to squeeze them in.
My current workaround is to set the upload speed to 100MBit/s, such that no movie will ever be reencoded due to a low upload bandwidth budget. Additionally, I cannot use the "Limit remote stream bitrate" setting, since this would make the server reencode to low bitrates though I'm trying to watch in my LAN.
I have several network interfaces on my server, I tried declaring them explicitly as local (192.168.1.0/255.255.255.0,10.8.0.0/255.255.255.0) and leaving the field blank. Both to no effect. The logs also show my external IP address as origin for the actually local streams of the signed-in client.
So, the question seems, is this a bug in the Win10 app, or have I misconfigured something?
Edit: PMS v1.2.7.2987, App v3.1.13-3d5de89c
Edit2: On my Android phone I do not have this problem, so it is very probable, that the error is in the Win10 App, isn't it? My phone acts similar