Server Version#: DS1821+ DSM 7.2-64570 Update 1
Player Version#: 1.32.4.7195-7000
Spoof message from Plex every 15 minutes or less.
We have been talking to Synology over this issue for some time, there have decided that we should pass on to Plex.
After a long investigation, we’ve discovered that Plex is sending out the messages on random ports. On network ports that are disabled I’ve tested this on a different Synology NAS running DSM 7.2 by installing Plex, as soon as it went live the spoof messages from the firewall started. I also tried the latest plex update 1.32.7195-7000, still same. We tried stopping anything from 169.254.41.0-255 range leaving the NAS, this result in Plex not working!
It also made no difference if the Plex was Live to the outside world or just internal. I’ve been running Plex on a Synology NAS for a very long time, never seen this issue until DSM 7.2,
The destination port, UDP 32412, is one Plex uses for network discovery of other players and servers via its GDM protocol. You can disable this discovery mechanism via Settings [Server Name] → Network (Show Advanced) → Enable local network discovery (GDM); uncheck that option and save your settings. Doing so may disable the broadcast messages.
For what it’s worth, that source IP address, 169.254.41.3, is what’s called link-local. It comes from a block of IPv4 addresses (169.254.0.0/16) which are automatically assigned when other automatic assignment methods (namely DHCP) fail for some reason (not strictly true, but true enough for our purposes here). (This is called APIPA in the Windows world.) I mention it because it could imply that there’s something strange going on with the network configuration on your NAS.
A further digression. When Plex communicates on the network, it doesn’t pick a source interface and source port directly (normally). Rather, it makes a generic API request to the network stack on the system saying “I’d like to send this data to this destination IP address and destination port.” The network stack then decides, based on several factors (not the least of which is its routing configuration) how best to send the data. So, a lot of this is out of Plex’s hands.
This is a Plex issue, when we were on DSM 6.2 no issue, on DSM 7.2 Plex is sending spoof messages that can’t resolve, if i stop/turn off plex then the spoof messages stop. I’ve already been through testing with Synology, they have said it’s a plex issue.
If we stop anything from 169.254.41.0-255 range leaving the NAS, this result in Plex not working!
