Plex integration: "Unable to play '[track]' - the connection to Plex was lost"

  • 1 December 2021
  • 40 replies
  • 2971 views

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Sonos version: 11.2.13

Plex version: 1.25.0.5282 (same issue encountered with 1.24.x.x)

Plex running in Docker container on an HP MicroServer serving music stored on same server. Plex app works fine and can browse/stream music from internal LAN and from outside LAN. Sonos app can browse music on Plex fine.

Until recently, I’ve been able to stream Plex music to SONOS without issues. It stopped working a couple of days ago. A new Plex update became available today and I’ve tried that with no success.

 

Problem description:

I believe the following are related issues as they started at the same time.

Variant 1:

Using the SONOS appFind and select track from Plex. When Sonos attempts to play track it reports error:

Unable to play track '<track name>' - the connection to Plex was lost.

Variant 2:

Using the Plex web app, the cast locates SONOS boxes but when trying to connect reports:

Playback Error
An error occurred loading the media being played on "<sonos device>".

 

Expected behaviour:

SONOS plays music as expected. Plex app is able to connect to and stream music to SONOS device.

 

Troubleshooting so far:

  • No errors detected in Plex logs
  • Tried rebooting all network devices
  • Tried reauthorising Plex with Sonos
  • Tried removing/re-adding Plex in Sonos (including removing app approval in Plex)

As far as I can tell, my network is fine. I was able to play tracks the other day and can’t play anything now. Plex app works as it should so don’t think the problem is there. I’ve run out of ideas to try now, and have been unable to get through to the support chat

Does SONOS or anyone else have any idea where I can go from here?

Thanks in advance.


40 replies

Userlevel 7
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We are unable to reproduce this issue. This is good for other users, but it makes it harder for us to help you all here.

@Ken_Griffiths - I’m told you have a different issue than the others - no NAT Loopback will prevent Plex from working.

@pwt & @timmyc - Could you please let me know your current Plex server network settings? Thanks.

We are unable to reproduce this issue. This is good for other users, but it makes it harder for us to help you all here.

@Ken_Griffiths - I’m told you have a different issue than the others - no NAT Loopback will prevent Plex from working.

Thank-you for looking into this issue @Corry P. that’s much appreciated👍. I will continue to press Plume to have the option to enable ‘Nat Loopback’ on their router. Plume have been canvassed about the issue previously and by others too, so I’ll see how that goes.

There are other ways to play the same music on Sonos, so it’s not a bother, other than perhaps the time spent trying to eventually get to the crux of the matter.

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My tier 2 colleague is now trying with the official Plex container as he wasn’t utilising it. 

Which made no difference. Still unable to reproduce.

@pwt would you mind creating a new test container with a new instance of Plex in it and test if that fails too?

I can do that, but not for some time, because I need to test using my remote Sonos S1 system, which is installed at a different property.

If I get time, I might flip my local S1 system onto a different network to the Plex server, and use that for testing.

I do appreciate you & your colleagues taking time to look into this.

That page is well out of date. The latest downloads for S1 are 11.2.13.

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I think the Plex issue maybe known to Sonos already, as there was a ticket open for investigation a short time ago. I’m basing that comment on this thread …

I’m still seeing the issue too from time to time with my Plex server and plex-pass.

This was a separate issue that was resolved as far as I’m aware. There’s a thread on the Plex forum about it - seemed to be that Sonos’ Plex integration was passing a malformed request string to the Plex API which is now fixed. I’ve not seen this for a few weeks now. https://forums.plex.tv/t/unable-to-browse-music-using-sonos-with-pms-1-24-1-4931/740590

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Hi @Ken_Griffiths 

Fantastic! Glad to hear it! Thanks for updating the thread.

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Quick update on this…

Spent over an hour on the phone with Sonos support, who basically went through same troubleshooting steps I had. Very thorough and helpful but unfortunately couldn’t identify any issues their end and suggested it might be a ‘Plex account issue’. (Not entirely sure what that means!)

Anyway, checked out the Plex logs again and there’s a couple of messages related to TLS:

CERT: incomplete TLS handshake from <my router IP> no shared cipher

Based on this, in Plex, I changed the TLS setting from ‘Preferred’ to ‘Disabled’, and boom, I can play music again!

There’s also an option in Plex ‘Strict TLS’ which forces only the most secure ciphers, etc. This seemed to have no effect.

I haven’t solved this fully, so need to investigate further, but my suspicion is that Sonos is using an older TLS cipher that’s been deprecated in the latest Plex version.

Will update again when I find out more.

Oh, one other issue - although I can now play music by disabling TLS (which I don’t want to do long term), the dreaded ‘Unable to browse music’ error has reappeared!

Researching online has led me to think the issue is possibly related to my router in my own case, which is ‘Plume WiFi’ and the suggestion from others, is that my router does not support ‘NAT Loopback’ and that is blocking the Sonos service from working. 

A passing observation: Unless the Plume is in bridge mode you’ll be in double NAT, assuming there’s an ISP router. Forwarding inbound traffic therefore wouldn’t work, at least without jumping through some extra hoops.

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Addendum to my previous - I don’t actually have TLS set up on this setup, so not sure why my TLS was ‘preferred anyway’. Still, it’s another avenue to investigate when I get time.

Userlevel 7
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Hi @pwt and @Ken_Griffiths 

Thanks for those diagnostics - I’ve forwarded them to our engineers who will investigate the issue.

Userlevel 7
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We are unable to reproduce this issue. This is good for other users, but it makes it harder for us to help you all here.

...

@pwt & @timmyc - Could you please let me know your current Plex server network settings?

Thanks.

Did you test access from an S1 system to an external Plex server, i.e., one on a different network to the Sonos system? I have no issues when my Sonos systems are on the same network, with either S1 or S2.

Note also that all the native Plex clients connect without problems when remote.

I’ve attached the network and remote access settings as screenshots below. I have port 32400 on my router forwarded to the Plex server.

Now, looking at the ‘Strict TLS configuration’ setting (an option I don’t remember seeing in the past), I’m wondering whether relaxing this would fix the problem. Unfortunately, I can’t test it at the moment.

 

Userlevel 7
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Hi @pwt 

Thanks for that. Yes, we tested a speaker on a mobile hotspot connecting via LTE to the Plex server. Our Plex settings match yours, and Strict TLS doesn’t appear to make any difference.

Are you running the native Plex server, or on a Docker Container?

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Hi @pwt 

Thanks for that. Yes, we tested a speaker on a mobile hotspot connecting via LTE to the Plex server. Our Plex settings match yours, and Strict TLS doesn’t appear to make any difference.

Are you running the native Plex server, or on a Docker Container?

It’s in a container, running with ‘--net=host’, so it should behave from a networking perspective as if it’s running directly on the host.

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Hi @pwt

It’s in a container, running with ‘--net=host’, so it should behave from a networking perspective as if it’s running directly on the host.

And we’re doing the same. We still can’t reproduce the issue - though it seems related to SSL. 

Hopefully, more information will come to light soon. Until then, being unable to reproduce, we’re unable to continue.

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Hi @pwt

It’s in a container, running with ‘--net=host’, so it should behave from a networking perspective as if it’s running directly on the host.

And we’re doing the same. We still can’t reproduce the issue - though it seems related to SSL. 

Hopefully, more information will come to light soon. Until then, being unable to reproduce, we’re unable to continue.

Thanks. Just to check: you’re testing using an S1 Sonos system?

If so, this is really odd. It used to work perfectly, but stopped doing so several months ago, despite no changes in networks or other relevant configuration settings -- other than normal software updates to Sonos and Plex.

I did wonder if it might be as simple as a certificate expiry, but if you’re not able to reproduce the issue, it’s not that.

Userlevel 7
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Thanks. Just to check: you’re testing using an S1 Sonos system?

If so, this is really odd. It used to work perfectly, but stopped doing so several months ago, despite no changes in networks or other relevant configuration settings -- other than normal software updates to Sonos and Plex.

I did wonder if it might be as simple as a certificate expiry, but if you’re not able to reproduce the issue, it’s not that.

Yes - S1.

My tier 2 colleague is now trying with the official Plex container as he wasn’t utilising it. 

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My tier 2 colleague is now trying with the official Plex container as he wasn’t utilising it. 

Which made no difference. Still unable to reproduce.

@pwt would you mind creating a new test container with a new instance of Plex in it and test if that fails too?

Starting this morning after Plex updated to v1.25.3.5385 I’ve started to have exactly the same “incomplete TLS handshake” message appear in the logs when trying to play anything from plex with Sonos. I have the same version of Sonos, 11.2.13 S1 and I can’t upgrade to S2 because I still have a Play5 (Gen 1).

 

Was anyone able to find a solution that did not involve disabling TLS in plex?

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(Following this on both forums too)

It appears that the beta of Plex (post 1.25.3.5409, and so presumably the next release) removes the option to disable TLS so this will not be a workaround for much longer. (Also, disabling TLS prevents use of the Plex web app, app.plex.tv, from outside the home network).

My guess would be that Plex no longer supports whatever TLS ciphers are used by Sonos. I don’t know the full list of ciphers supported by Plex, but I suspect they’d be loathe to reintroduce any legacy ciphers that have presumably been depracated for security reasons. Therefore, I think the question is will Sonos update v1 of the app to support more modern ciphers supported by Plex? I think this falls into the ‘security and bugfix’ category rather than new features so hopefully it will be looked at.

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Hi @timmyc 

I’m glad to hear that the issue, for you at least, now seems to be resolved - thanks for sharing those details, and for updating us all here.

Is anyone still able to reproduce this issue after reboots and updates?

Yes, still not working for me. Latest versions of everything.

Userlevel 7
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FYI supported TLS ciphers that Sonos support are here: https://developer.sonos.com/build/content-service-get-started/security/

Since the current version of S1 is 11.2.6, I assume you are on S2.  The current version of S2 is 13.4, so the first thing I would do is upgrade then retest.  No point in doing anything else before that.

Not sure if you’re up to date with Plex.

The OP has Play:5/gen1. 

The OP has Play:5/gen1. 

 

Then if on S1, I don’t know how OP is on version 11.2.13.

https://support.sonos.com/s/article/4941?language=en_US

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It's definitely 11.2.13. Yes, I'm stuck on S1 for now as I've got a couple of legacy devices. Don't think that's the issue though, as it's been working fine previously.

Plex version is the latest.

 

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