Sonos making thousands of SMB3 connections to Synology

Not sure if anyone else is experiencing issues with Sonos Music Library and the Synology NAS becoming unresponsive or very sluggish, or with random speakers disappearing from the S2 app.

I recently enabled the Music Library feature in Sonos (before the 13.4.1 update in Dec 2021 which introduced SMB3 support). At that time, I configured my Synology NAS to use SMB1 to allow the connection to work. I was on DSM Version: 7.0.1-42218 and running S2 13.3.2. Somewhere around 11/25/21, my Synology started going offline and become unresponsive. I was running a DS1517+ with 2GB of RAM and noticed that the SMB process was eating a lot more RAM than usual. Also, started seeing thousands of connections from the Sonos speakers, multiple times for each speaker. My Sonos updated to 13.4, but the issue still remained.

I opened a case with Synology and they determined that the Sonos speakers were opening hundreds of connections per speaker and leaving the connections open. This was slowly draining the memory until the NAS would become unresponsive.

On 12/7/21, S2 updated to 13.4.1 which introduced the SMB3 support. I turned off SMB1 on the Synology NAS and still saw the hundreds and thousands of connections. I would also see the speakers attempt an SMB1 connection still which was denied by the speakers. For testing, we tried leaving SMB1 on, but still saw the large amount of connections from the Sonos speakers.

I ended up switching to a newer DS1621+ with 8GB of RAM and the issue still continued to happen, but took several days instead of just one. At one point, the number of active connections from Sonos was near 4000.

After switching to the DS1621+ with more memory, the issues started getting worse on the Sonos side. Several speakers would start to show up as ZP100 (would be various speakers and not always the same ones). This marked these speakers as incompatible with the S2 app and so I couldn’t do anything relating to the music library (like remove it) until the affected speakers were rebooted. If you tried going to http://<ip of speaker>:1400/xml/device_information.xml nothing would show up, or just the XML banner stating “This XML file does not appear to have any style information associated with it. The document tree is shown below.” The speakers were acting similar to the old NAS where they would start to become unresponsive. I can only guess that with the hundreds of open connections to the NAS, the memory utilization would get very high and the speaker would stop responding correctly.

After rebooting the speaker that showed up as a ZP100 you could then hit the XML page and the speaker showed up correctly as a Sonos One. I would also get some speakers that would just completely drop from the application, but after a reboot, they’d show up just fine.. In all cases, my wireless controller showed all speakers connected on the network and they all responded to pings. After a reboot of all the speakers, they all showed up correctly in the S2 app and could all play music from the Synology. Also, after a reboot of the speaker, all the connections would slowly drop on the NAS and memory usage would return to normal.
 

The whole system would run fine for a couple of days and then the connections would start appearing on the NAS at various times (not just at the 2am re-indexing time). I also noticed that whenever I had the S2 app up and when I would explore a Sonos playlist that contained music from the NAS, I would get SMB1 failures in the NAS logs for the associated speaker. I believe that the code is still set to use SMB1 for some functions and is getting blocked by the NAS..

If I disable the Music Library, all the speakers stay connected to the wifi network and I can stream music with no issues for several days. The memory on the NAS remains at normal levels and doesn’t climb over time. I still see SMB1 connections whenever I pull up the S2 app as long as the Sonos playlists exist that point to music on the NAS, even if the Muisc Library is disabled. I still think the Sonos code is trying to use SMB1 to update something either with album art or the track icons and is having trouble. If I browse to the album directly under Music Library, the album art does show correctly. It just seems to be the track icons in the playlist has trouble populating. These playlists were created by selecting various tracks in the Music Library and adding them to the Sonos playlist.

I have tickets open with both Synology and Sonos and currently waiting to hear back from Sonos after giving them countless diagnostics and logs. It seems that the diagnostic logs don’t show the connections to the NAS and so support doesn’t have any visibility into the problem other than looking at the thousands of connections in the Synology logs that I’m providing them.