I am running 19.07.5 on a Netgear Nighthawk X4S R7800
I have Plex media server running in a docker on IP 192.168.1.25, it has automatically opened external port 11878 on my router via UPnP and directed this to 32400 internally.
Accessing Plex remotely works fine.
But on my LAN I notice when I go via https://app.plex.tv as recommended I only get an indirect connection so I'm limited on streaming as its going via a Plex relay.
Digging in the Plex logs it seems the issue is this:
Aug 17, 2021 12:52:36.620 [0x147d7a1f1b38] WARN - [EventSourceClient/pubsub] HTTP error requesting GET https://XX-XXX-XXX-XXX.4c630fb08662455d9278cd86cb416b5d.plex.direct:11878/identity (7, Couldn't connect to server) (Failed to connect to XX-XXX-XXX-XXX.4c630fb08662455d9278cd86cb416b5d.plex.direct port 11878: Connection refused)
XX-XXX-XXX-XXX is my WAN IP redacted
I have plex.direct in my domain whitelist and no DNS rebinding issues reported in the logs and I can resolve the above URL fine using an nslookup.
So as a test I run from another system on the LAN:
curl -v telnet://XX.XXX.XXX.XXX:11878 and I get connect refused (same as Plex)
However if I then add a port forward rule for 11878 to 32400 in Luci then the above curl command succeeds and Plex also has a working direct connection.
Why is there a difference between the UPnP port forwarding seemingly not working from my LAN but manual port forwarding working fine ?