After installing Plex Server v1.3.3 my internal firewall reports started showing 100k plus attempts daily to connect back to Plex from other machines in my internal network.
Sniffing the packets, they are UPnP responses. So, something new in 1.3.3 is issuing a UPnP discovery message which other servers are trying to respond to, but because of my internal firewall, they never reach Plex.
Why is this needed and how can it be turned off.
Cheers.