I have a similar setup to you. Here is what I get...

The old Sonos IOS app and Sonos Windows desktop app always finds and displays the Plex content OK.
The new Sonos IOS app “nearly always” displaying no content when selecting the Plex service. If I then select the Plex service again sometimes it displays the Plex content sometimes it requires more attempts.
It is almost as if the new Sonos app is timing out before the Plex info is being returned.

Ross.

Thank you for that. It’s very discouraging to hear, but I appreciate the information. The only reason I bothered learning to install and configure Plex was that the new Sonos app has stopped showing the content I was sharing from the NAS via SMB, and I hoped that sharing through a media server would be an improvement. Apparently it is not.

Like many people here, I am having a hard time understanding how Sonos does not think that (accidentally?) removing access to so many people’s content libraries is not an emergency needing an immediate fix. I’m sure if that app release had somehow broken the ability to listen to Spotify or Audible, they would have posted messages immediately saying “sorry! we’re working on it!” and it would have been fixed by now.

Same here.  I was just setting up my new speakers and was having the hardest time connecting Plex,  when I came to the Internet for answers. 
 

Came looking for a solution as have the same issue on Android.

Just started using the new app and no Plex content (plus had to remove all my favourite radio stations as they're greyed out and no longer fiction).

I use Plex a lot, streaming through the browser at work or my desktop for music, Plex amp on my phone when I'm out, a Chromecast on my TV for films and the TV channel tuner - all without issue, so I'm fairly certain the fault lies at Sonos's door.

Tidal, YouTube Music, Spotify, SoundCloud and Mixcloud all work fine, I've reauthorised Plex, but made no difference.

As u/rosswells127 mentioned, reopening Plex several times gets it to work, but it is several, not one or two, which makes it practically useless when you just want to pop a quick bit of music on.

>Edit]

And it gets worse, even when I've finally got it to show, won't play any .flac encoded content (the majority of my library), stuff from back when I was encoding in .ape is fine, even straight .wav files, so it's not a sizing/bandwidth issue, just straight up refuses .flac.

Why are hardware companies always so bad at software, and get worse, the older apps had no problems, and a better UI, why waste money on making things worse?

You can stick all the ads for new Sonos products you want in the app, no way will I be buying more of this trash.

I see Plex in the new Sonos App and the content from my Plex server is seen & plays fine. No problems with the service. See attached.

You didn't see the bit where people are saying mobile app, not desktop app..

u/Vinndalf actually states their desktop app is fine. 

I’m using the mobile App - there isn’t a new desktop App, only a Web App… I’m using the mobile App on an iPad.

It works on my iPhone too.

My apologies, the video looks more like the desktop app.

But, happy yours works, not sure how they helps us where it doesn't...

Just for completeness here is my iPhone XR Sonos App and Plex server service from my NAS…

I’m just saying the new Sonos App and Plex service works fine here, so it’s maybe possible that your issue may lie elsewhere, perhaps?

Hi @Ken_Griffiths, unrelated/related question for you. Two some-odd weeks back you were kind enough to try an experiment on my behalf: creating a Sonos Favorite of a local library album (Genesis, Trick of the Tail) on the new Android app. Was that album on your Plex server?

I ask because in my case the local library album is on a network share, and my debugging efforts have not yet been successful. I’m keen to narrow things down in my quest.

My NAS library and Plex library are the same music library share - is that what you’re asking @press250?

There’s just the one set of folders/files that both the Plex server indexes (amongst other things - movies/videos/photos etc.) and the Sonos library points to the same folder structure - using a dynamic SMB v2 to v3 share. Screenshot of some of my NAS folders attached.

Hi @Ken_Griffiths, not trying to be complicated! I’m not a Plex user, so I was under the impression that bringing up a Plex server would replace using a network share … tho’ it sounds like you have both options pointing at your entire music library.

In any case, I think you’re saying that your experiment—marking Trick of the Tail as a Sonos Favorite—was via network share (didn’t have anything to do with Plex) so it was the same for both of us. Well, not entirely the same as it works for you but not (yet) for me. 

I can’t recall, @press250, can you kindly point me to our earlier discussion on the matter, just to jog my memory. 

@press250,

I did just try it by the way and ’Trick of the Tail’ does indeed add to my Sonos Favorites, from my local library (not Plex), but it’s artwork/cover is not displayed correctly - was that the issue we perhaps discussed previously? 

The album/tracks are there though and it will play after adding the album as a favorite.

@Ken_Griffiths 

Good to hear that your Plex access is working fine from the new app! Perhaps your Plex service is responding quicker than mine and others with this issue.

I am also using iPad on local network with Plex running on my Synology NAS using SMB 2 and above.

When I select Plex from the services list using the new IOS app I get a blank screen, if I try again it sometimes works, it will generally always work on my 3rd attempt.

I have no problems accessing Plex using the Sonos web app, the old Windows app, the old Sonos app (still running this on my iPhone), SonoPad app on my iPad, Plex app on my iPad, PlexAmp app on my iPad etc. So only issue is from the new IOS app running on my iPad.

I have a lot of Sonos devices on my network and have never suffered from any network issues etc.

I think the new Sonos app is timing out early when waiting for a response from the Plex service.

In the meantime I am tending to use SonoPad or PlexAmp to access my Plex music library on my NAS. I can also use SonoPad to access my Sonos music library which is also on my NAS (same folder as Plex library). SonoPad has direct alphabetic to artists or albums which is a feature still missing from new Sonos app!

I hope Sonos that can make changes to the new app to allow me to access Plex trouble free via their app, but at least I have plenty of work arounds in the meantime.

Ross.

@rosswells127,

Strange that you’re getting intermittent results with access to Plex. I’m not experiencing any difficulties with Plex on Sonos. Are you running the latest version of Plex server? My version here is v.1.40.3.8555 -

I do have a couple of NAS boxes with Plex sever on both and each seem to be working okay with the new Sonos App. Could there be an issue perhaps with NAT loop-back on your local router - perhaps try the router ‘with’ and ‘without’ UPnP (auto-port forwarding) enabled and see if that makes a difference.

@rosswells127, 

Another after-thought - maybe try is to disable any power-management settings on your NAS, just temporary, and see if that changes anything, that said my power-management settings are just set at the default for my NAS, but it maybe worth seeing if that changes anything.

@Ken_Griffiths 
1) Was running Plex Server 1.40.2.8395, so have just update to latest.
2) I do have HDD hibernation set to 20 minutes, will temporarily disable as you suggest.
3) uPnP is enabled on my router, will temporarily turn off.
Will see how that goes and report back.
Thanks, Ross.

@Ken_Griffiths 
Ran new IOS app on iPad, selected Plex service → blank screen.
Re-selected Plex service → Plex results displayed as expected.

Ran the web app on my PC, selected Plex service → Plex results displayed as expected.
So unfortunately, the suggested changes didn’t make any difference in my case.
Weird one, but will continue to work around by using web app or SonoPad in the meantime.
Ross.

Ah sorry to hear those suggestions didn’t work. It does sound though like the App ‘Plex’ connection is hindered by some kind of power management in your case and the connection is timing out on first launch. 

I left my NAS all evening, having watched the England/Serbia Euro game, that started at 8pm and went and opened Plex in the App around midnight-ish and it opened without issue. So I’m not sure it’s the App.

However, that said, in my own case, the NAS/Plex server here uses a dual gigabit teamed (round robin) network connection, so it’s a pretty fast link. So maybe it’s a case the Plex service in the Sonos App needs to wait a little longer for some server connections to respond.

@Ken_Griffiths 
I have run old 16.1 app on my iPhone. The Plex service works really well there.
One thing I failed to mention is that on the old 16.1 app I can also select ”Other Sources” and can then access one of my friends music library on his Plex server which he allows me remote access to.
If I try this on the new IOS app on my iPad it says “Something went wrong, try again”. Trying again never works, it just repeats the message.
So perhaps when I initially load Plex on the new app it is also trying to populate the “Other Sources” details and timing out. That may be a difference between yours and my setup?
Ross.

@Ken_Griffiths ,
Great that you have such a fast network. Mine is only a single 1gigabit connection.
My NAS is also only a DS224+ and no SSD drives installed.
I tend to agree that the new app is probably timing out too early.
Thanks for your help/suggestions.
Ross.

Your nas and network are plenty fast. Try ruling

out your hard drives hibernating causing the time out:

Control Panel > Hardware & Power> HDD Hibernation, and select none from the first drop-down menu.

@Bumper 
Thanks for the suggestion , as per @Ken_Griffiths suggestion above I turned off Hibernation as per your suggestion above and re-ran my test and unfortunately it made no difference.
FYI: Ther Sonos Plex service always ok via SonoPad app, old Sonos 16.1 app and new Sonos web app. It only times out using new IOS app.
Ross.