I have a strange issue involving remote access and preferred network adapter:
I’m running Plex on a MacMini M1 which has a network connection via ethernet and via Wifi. The Wifi is necessery because i would like also to use AirPrint functionality via the Mac.
In Plex settings I’ve set the network adapter with ethernet as the prefered one. But If I check remote access settings the IP from the Wifi connection ist listed. In my opinion this should not even work, because in my router I port forward to the IP adress of the ethernet adapter and not the Wifi. And nevertheless remote access works… What could be wrong here? Is Plex just showing the wrong IP in Remote Access? And what else can I do to force Plex to use the ethernet connection?
To understand what you’re seeing it’s important for you to understand exactly what “Preferred network interface” does.
First, it only controls which IP address (based on the interface) is advertised for local client connections. That is, the IP address assigned to this interface is advertised to local clients so that they know how to connect to your server. Even considering that though, it’s only a preference, it’s not exclusive. See the next point.
Next, it has no bearing whatsoever on remote access. Plex always listens on all available interfaces for inbound client connections:
LISTEN 0 1024 0.0.0.0:32400 0.0.0.0:* users:(("Plex Media Serv",pid=651795,fd=10))
So even if you have a preferred interface set, if a connection attempt is made to any other interface on which PMS is listening, it will be accepted.
Having said all that, maybe Plex is just showing the IP address of what it considers to be the primary interface for your system (you can look in your server logs if you have Debug enabled to see what it considers to be the primary interface). Or maybe a remote connection really is making through to your wireless interface somehow (do you have UPnP enabled on your router?).
If you really want to be sure where your traffic is terminating I’d recommend a tcpdump specifying TCP port 32400 on that interface. For example:
sudo tcpdump -i en0 -A -vv tcp port 32400
Maybe add an appropriate “and host x.x.x.x” filter as well. Have a look at the traffic and see if it’s what you expect. Alternatively, tcpdump the wireless interface and ensure it doesn’t have traffic you don’t expect on 32400.
[Edit]
Added the word “not” in front of “exclusive.”
A maybe-easier option than tcpdump: netstat -nb | egrep "(rxbytes|32400)"
The WiFi used for AirPrint - does that network have a router, a gateway, a connection to the Internet?
I’m curious what the adapter priorities are on the Mac itself. In System Settings → Network, there’s a little ... drop-down menu, and you can Set Service Order.... You might want the Ethernet to be above the WiFi.
You could share the output of netstat -rn -f inet | egrep "(192.168|G|S)". It would be interesting to see if the Mac itself is prioritizing the Ethernet for Internet-bound traffic.
The Plex server logs likely have useful information, especially a couple minutes after restarting the Plex Media Server app. It does some network probing and discovery.
Thank you guys very much for your input and your efforts!
I’ve now decided to move the printer to another machine and deactivate the wifi on the machine with Plex… After a restart of Plex, remote access is showing the network adapter correctly since there is only one (the with ethernet that I want) anymore…
