Update as of June 15th.  I was quite frustrated with the apparent lack of progress ...   I went to my window’s PC and noticed that there was an application update.   I updated that then I noticed the NAS (I have a Synology Play) wasn’t listed… I reconnected the NAS via the PC app then updated.reindexed the Music Library then it showed up on my Android App as a source.

Summary of steps that worked for me:

1. Update the windows app on the  PC.
2. Reconnect the NAS
3. Update Music Library
4. After this… it appears on the android app.

By “app” do you mean the standalone controller that you download from Sonos, or the web app that you access via a browser.

The one you download has Music Library management functions. 

This workaround worked for me as well.  Thank you for sharing.  After over a month of being unable to access my local library through the Android App, I can now at least play my library again through both the Android and Windows apps.  The user experience of the Android App is still terrible, and my faith that local library access won’t be broken again by a future update is very low.  However, at least my 20 years of investment in Sonos hardware isn’t a total waste.  Yet.

What will sonos do about the problem that i can not reach my NAS library anymore since i have the new controller on my phone. How is it possible that a company can deside to make changes in some of there appliclations, that makes a lot of prefect stuff useless. is there a solution to solve the problem? 

I just bailed on Sonos and sold all my equipment after a month and a half of not being able to play from my local library, and invested in WiiM. But try this one on for size… if your internet goes down, so does your ability to play local music. That’s because the new app is reliant on the internet to check in with Sonos web services in order to function. That’s where things are going. Perhaps they will slowly start eliminating features like this in favor of streaming? There’s no telling. But this wasn’t the case with the 16.1 app, as it could still function in an environment where internet was not available. Being able to locally play music was my whole reason for getting Sonos in the first place… I’m glad to see it’s back… sorta.

This is not the case for me. I have a separate modem and router and if I power off the modem, I can still play music from my local NAS library using the Sonos App (iOS -iPad) and change tracks/speakers. The local library shows up and plays without any problem.

While your internet is unavailable, try launching your app from scratch. I found if you had your app open at the time the internet went out, you could still control things.  But if you launch from scratch, it will exhibit problems and won’t be able to load. Unless they recently fixed that as well.

Just let the services time-out (although it’s not necessary) simply goto the music library under the ‘your sources’ area of the Home Screen in the App. The library is still accessible - I understand the library index is stored on the associated product. I’m able to play to my speakers from the local NAS, obviously the WiFi/LAN just needs to be accessible.

I can confirm this behaviour. I blocked the Sonos devices from connecting to the internet via MAC address filtering on the router (I have a separate router and modem setup). They continue to work correctly via the old app and desktop client as they remain part of the local network.

The new app works for a time, but after an hour or so it stops seeing the devices and sits there with a bunch of flashing/loading placeholders as if the system doesn’t exist. Meanwhile they’re merrily playing and being controlled by the old apps.

For some users there’s definitely a dependency on an internet connection when using the new app.

It does work, I’ve just quickly tried it again. I took a few screenshots. it’s just not the best user-experience, i guess, without the internet connection.

In any event, the Sonos system requirements do state an internet connection is required to use their system.

For you yes, but for me it doesn’t. It’s almost as though this buggy, half-baked update and app might work differently for different people due to any number of variables!

This is the app after connecting to the system it tells me exists on my local network. All I’ve done is deny the two Sonos Rays in question access to the internet via MAC filtering.

The same system is working perfectly, right now, via the old S2 app on another device, despite the two Rays having no internet access. If I remove the MAC filter the new app will instantly work again. 
 

I’ve seen exactly the same behavior, @Superunknown. Last month I poked and prodded the new app in an effort to better understand its interactions with sonos.com and the handful of third-party servers. At least one of those servers implements “feature flags” for the new app: we’ve already documented the counter-intuitive behavior of alarms and sleep timers disappearing from the menus when DNS privacy filtering blocks access … 

FWIW, I duplicated your MAC filtering result by blocking access to the third-party servers.