I’ve just run the same procedure here but with the difference that I’m also observing SSDP IPv6 traffic as my LAN is fully IPv6 enabled. Plex has IPv6 disabled in the Network section, however.
- PMS 1.15.2.793 on my server with “manually specify public port” selected in Remote Access and the port forwarded on my router
- UPnP enabled in minupnpd on my router
I started the PMS server and, after an initial burst of processor activity from a number of Plex processes, I saw the plex media server process go up to around 100% cpu utilisation. I stopped the packet capture (and PMS) after leaving it in this state for a few minutes and examined the output in wireshark.
I can see the router doing SSDP NOTIFYs and OKs. I see the server IP that PMS is running on doing multicast SSDP searches every now and again (obviously can’t easily tell in wireshark what process is generating this traffic, but I’ve stopped as many services on the server as I can) and receiving a few OKs from my Hue Bridge. There’s also quite a bit of multicast SSDP traffic from assorted Sony wireless speakers around the house.
I then uninstalled PMS 1.15.2.793 and reinstalled 1.14.0.5470 and followed the same steps. There’s no discernible difference in the traffic patterns I’m seeing but the high CPU utilisation is not observed.
FWIW, I also ran up a 1.15.2.793 server on my MacBook Pro and observed the same behaviour when restarting minupnd with upnp enabled. Regressing PMS on the MacBook Pro to 1.14.0.5470 and running minupnpd with UPnP enabled did not produce the high CPU behaviour in the plex media server process. Wireshark dumps during this testing showed similar results: a mix of multicast discovers, notifys and OKs.
FYI, your colleague @sa2000 was investigating the issue as presented on macOS in this thread and seems to have come to the same conclusion that there’s nothing obviously wrong in the network traffic.
