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Question

Music Library on router USB drive

  • January 28, 2026
  • 27 replies
  • 117 views

been using Sonos for years and suddenly, 1 week ago, I was not able to update my Music Library (usb connected to the Router as a NAS).

Sonos App says “//XXX.XXX.XXX.X/MP3_Router’ is no longer available. The device storing your music files may not be turned on, or the path may have changed.”

nothing changed, Router, network, settings…..any idea what it could be?

27 replies

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  • Prodigy III
  • January 28, 2026

What Sonos speakers do you have?


  • Author
  • Contributor I
  • January 28, 2026

1st room: 2 play 1 - Sub (Gen 2) - Beam (Gen 2)

2nd room: Play:5 (Gen 2)

3rd room: Symfonisk Shelf

4th room: Playbar

 

the fact is that I can see the network disk, connected with my computer and I can work on it, so it means the connection is working. Sonos App seems to loose often the path. Now I’ve just tried for the 5th time to re-connect the library and it’s working….very strange


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  • Prodigy III
  • January 28, 2026

The way Sonos works is one of your speakers is the ‘associated product’ and becomes the one responsible for adding music shares and re-indexing them. Certain speakers behave differently than others and won’t index from some NAS drives. Several of us on here have experienced this with the Era 300 for example. 

My guess is that you’ve rebooted some of your speakers as you had issues and eventually a different one became the associated product and the re-indexing worked again. If you use either the Windows or Mac Sonos apps, the about my system window shows which speaker is associated. If you have the will/time to only have one speaker turned on at a time you could possibly see which one has the problem by triggering a re-index with just that speaker active. At least then you could raise a case with Sonos for them to look at, unless you’re happy to just reboot the problem speaker if indexing fails. 


Stanley_4
  • Lead Maestro
  • January 28, 2026

Good advice above. Sometimes things just get confused too. To avoid a support call to just be told to do a network refresh you can do one on your own.

Power down ALL Sonos.

Reboot router and controller, wait until fully ready.

Power up your Sonos.

I might try only powering up the Beam at first (newest one) and trying the process with just it active to simplify the situation. If it works power up the rest, if it fails then do the diagnostic and support call option.

 


  • Author
  • Contributor I
  • January 28, 2026

Indeed i noticed the library now is visible and updated and the speaker associated is the beam; will check next time the network disc is no more visible what’s the associated speaker


MoPac
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  • Headliner III
  • January 28, 2026

 So I would like to understand indexing better than I do now.  My Associated Product is a Beam.  That’s one of five rooms.  When the library indexes is it indexing only to the Beam and the other speakers look to the Beam to see the library?

 I purchased a new 300 a month or so ago.  It refused to play my indexed library.  So I sent it back to Amazon.  So as Ian_S suggests if I had unplugged every room except the new 300 then the 300 would have become the Associated Product and I could attempt an index under those conditions.  Is that correct?


Airgetlam
  • January 28, 2026

My understanding is that the indexing is done by a single device, then the result is copied to each (other) device. Which can take time, depending on several factors, not the least of which are file size and communication speed between each Sonos device. And possibly others, too. 


AjTrek1
  • January 29, 2026

U know I’m going to disagree with a lot of learned people with the following statement:

I don’t believe that  the Music Library indexing is assigned to one specific speaker which as I read all your comments if that one speaker is disabled then the indexing fails. I could be wrong but I believe the indexing takes place at the source like a NAS and then that information is shared with all speakers except surrounds and subs. Furthermore I can’t find any documentation that a specific speaker is selected as the primary device.


Airgetlam
  • January 29, 2026

Since the software (Sonos) isn’t installed on the NAS, I don’t understand how the list, which is all Sonos maintains, can be built there. But I’m no expert, either. Help me understand. 


Airgetlam
  • January 29, 2026

Oh, no argument about documentation, though. I think it’s understood knowledge that leads to my post, not something I can point to. I’m certainly open to discussion ;)


Stanley_4
  • Lead Maestro
  • January 29, 2026

No documentation here, just my poor memory of past discussions.

Indexing is done on the speaker you are connected to, unless the Sonos software feels it is underpowered or too low memory to do the index well, then the software steps in and assigns the index to a better speaker iv available.

I don't think there is a way for the user to be sure where the index is generated. The reason I suggested powering down all but the most capable speaker. Get it done and then let it propagate once the others are on-line.

 

Again no way to actually tell on the sharing once the index is generated but based on my Linux knowledge I'd lean to expecting "rsync" to be doing it. Very powerful file sync tool with a lot of optimizations to reduce cpu and memory load and minimize bytes pushed across the network.


Stanley_4
  • Lead Maestro
  • January 29, 2026

Since the software (Sonos) isn’t installed on the NAS, I don’t understand how the list, which is all Sonos maintains, can be built there. But I’m no expert, either. Help me understand. 

My NAS is mounted read-only so no possibility of Sonos doing anything there.


Airgetlam
  • January 29, 2026

Certainly my understanding was that Sonos had no ‘write’ privileges beyond its own domain. I’ve always taken the assumption that playlists were stored in the RAM of the speakers…one of the various things that get erased when someone does a factory reset. And in this case, playlists are essentially the same thing as NAS data…or any Sonos stored pointers to existing data, whether it is NAS located, or otherwise. If the data was written to the NAS in some way, then the reset would be able to re-load that data. 

But I’m neither a programmer, nor do I have access to Sonos’ code base, so these are assumptions. 


Stanley_4
  • Lead Maestro
  • January 29, 2026

I think you are right, anything that survives a power-cycle is in internal persistent memory.

The factory reset wipes the user and system data portions of that memory while not touching the operating code portion.


AjTrek1
  • January 29, 2026

I can’t debate the issue either. I’m possibly wrong about where the indexing takes place. However, I can’t find or fathom any logical reason why a single speaker would be responsible. That premise suggests that if I removed the speaker for whatever reason my library would be broken and you know that l’ll upgrade a speaker in a New York minute 😂.


Airgetlam
  • January 29, 2026

Heh. No, because (IMHO) the ‘list’ is copied from the originating speaker to existing data on all other speakers…so no single speaker holds the only data about the system. The same, I think, applies to the rest of the information, so it never exists on a single place, and that the loss of any device, including a controller, has no affect on the ‘system’. All Sonos devices share everything…which is one reason there’s so much crosstalk (although not the only reason).

So there is one ‘device’ that does the scan, but once it’s complete, the data is distributed to all. 

Again, just my guess as to how Sonos works. All the caveats apply, as before ;)

 


AjTrek1
  • January 29, 2026

@Airgetlam (or anyone) 

OK…riddle me this Batman 😊

Jokes aside…How do I determine the target speaker for indexing🤔

 


Airgetlam
  • January 29, 2026

I don’t think you can. I think it’s the first speaker in the ‘list’ maintained by your Sonos system. I don’t think there’s any control by the user, despite several posts from people claiming they’ve done so. 
 

I suppose you could unplug all but the desired device, then manually run the scan, then plug back in all the rest of your system so that the data gets copied over, but I don’t think there’s any way to ‘define’ which device is used. I don’t even think there’s any way software looks for the ‘fastest CPU’, or the ‘most available RAM’ to use….but I’m just hazarding a guess. 


  • Author
  • Contributor I
  • January 29, 2026

Probably, based on Sonos policy (like Apple) if the connected speaker is an old one, the connection with the nas is lost and the indexing is not working anymore. This could be the reason why keeping on trying, after dozen of tentatives it works. It’s only a thought but don’t forget tons of problems app faced during the last 2/3 years, so would not be surprised if this is a “new” app issue due to the fantastic development of the last 20 versions….


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  • Prodigy III
  • January 29, 2026

The target speaker for indexing is the associated product. In the pre-May 24 phone/tablet apps, the ‘About your system’ used to show this but no longer does. The Mac/Windows apps being of a certain vintage still do. With all the testing I have done in the last few weeks, the associated product and the behaviour of indexing correlates exactly. The Era 300 is almost guaranteed to become the associated product for me as it boots so much quicker than anything else. So post firmware updates (quite regular) it will assume that role until I power cycle it, leaving about 5 mins between off and on so the other speakers elect a new ‘associated product’. The first speaker to power on will become the AP until it power cycles. 

As pointed out above, Sonos can’t store the index on a NAS as (Era 300 aside) the index takes places even if the music is on a read-only share. Also if you are able to to track NAS write activity during an index you’ll see there is none. 

 

The index is propagated to all speakers which is why there’s a limit on no. of tracks as it has to be able to reside on all speakers. I don’t know what the memory limit is, and if you have lots of devices with more memory I don’t know if the system allows it to be bigger. (Would be nice for some I’m sure) Sonos don’t seem that bothered with enhancing the local library experience. 

 

The controllers use the basic index from a speaker (with varying degrees of success on search) to display metadata and they then (mostly) access the NAS directly for stuff like album art to make it all look pretty, as it would make no sense to store that on the speakers given the picture info is quite large relative to index info. 

 

This is a different approach to something like Minimserver which if installed on a NAS creates its own space where it does hold its index. However, it’s a server based product that distributes data in a different way. 

 

I can’t debate the issue either. I’m possibly wrong about where the indexing takes place. However, I can’t find or fathom any logical reason why a single speaker would be responsible. That premise suggests that if I removed the speaker for whatever reason my library would be broken and you know that l’ll upgrade a speaker in a New York minute 😂.

No, your library is not broken because each speaker has its own copy (for resilience and speed) and if the elected AP disappears, the system elects a new one from the remaining speakers. So everything continues to function. It would make no sense in a larger system for each individual speaker (at the same time when requested) to all try and generate the same index from the same source. Much more efficient and stable to have just the one source and propagate it to the others when done. That also removes the nightmare of different speakers getting different results (happening now) and then the controller software would appear to randomly show different things depending on which speaker it connects to. At least when it’s wrong, it’s the same wrong system wide as it stands.

It also means when you add a new speaker, it just receives a copy of the current index from other speakers. Again I know this is how it works as if it didn’t, when I added my Era 300, it would have failed to index due to various issues. Instead it received the library index but was unable to play any file as because it was built on another speaker, which was happy with SMB names where the Era 300 is not.

Finally, if each speaker didn’t have its own copy of the index, (we know its not NAS based as it can function with a read only music share) the system would not continue to function as you turned off each speaker. It does. And you if you power all speakers off, you can choose *any* speaker to power on, and that speaker will be fully functional without needing to run a re-index. That can only happen if each speaker has its own copy. If you don’t believe that, then keep the desktop controller running, and as soon as it detects the speaker, open the Manage Music Library Settings menu, and if a re-index is taking place it will tell you there. It won’t be. (and it takes much longer to re-index than it will take the controller app to see the speaker and for you to open the menu…)  


AjTrek1
  • January 29, 2026

I’m inclined to agree that I don’t think there’s a specific speaker assigned for indexing. If I were to guess I say it’s a speaker with the strongest WiFi signal at a given time or maybe one that’s wired.

The first speaker in my ‘about system” is an Era 100 in my garage. I doubt that it is the assigned speaker as there is a much closer Arc Ultra and/or Five to my router. Besides the speakers are listed in alphabetical order by room name. FYI, the speakers in my garage are named “Carport” all other rooms are in descending order of the alphabet (A-Z).

One more point...my stereo pair of Era 300’s have no problem playing music via my library (as the source) as has been mentioned.  Assuming I’m interpreting what has been said correctly. 

At the end of the day I’m not overly concerned about how the indexing is performed...at least not until it doesn’t 😂


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  • Prodigy III
  • January 29, 2026

I’m inclined to agree that I don’t think there’s a specific speaker assigned for indexing. If I were to guess I say it’s a speaker with the strongest WiFi signal at a given time or maybe one that’s wired.

The first speaker in my ‘about system” is an Era 100 in my garage. I doubt that it is the assigned speaker as there is a much closer Arc Ultra and/or Five to my router. Besides the speakers are listed in alphabetical order by room name. FYI, the speakers in my garage are named “Carport” all other rooms are in descending order of the alphabet (A-Z).

One more point...my stereo pair of Era 300’s have no problem playing music via my library (as the source).

Look on the desktop app, it will tell you which is the associated product. The order of the products appears the same, but the AP is not guaranteed to be the first product listed. In my system it is not. 

And we already know your Era 300’s worked because you already used the IP address instead of NAS name and also made the Sonos user admin… 


AjTrek1
  • January 29, 2026

I’m inclined to agree that I don’t think there’s a specific speaker assigned for indexing. If I were to guess I say it’s a speaker with the strongest WiFi signal at a given time or maybe one that’s wired.

The first speaker in my ‘about system” is an Era 100 in my garage. I doubt that it is the assigned speaker as there is a much closer Arc Ultra and/or Five to my router. Besides the speakers are listed in alphabetical order by room name. FYI, the speakers in my garage are named “Carport” all other rooms are in descending order of the alphabet (A-Z).

One more point...my stereo pair of Era 300’s have no problem playing music via my library (as the source).

Look on the desktop app, it will tell you which is the associated product. The order of the products appears the same, but the AP is not guaranteed to be the first product listed. In my system it is not. 

I’ve looked at the Desktop App under “Manage > Music Library Settings and there is no indication of a specific speaker assigned for indexing. FYI, I use macOS Tahoe 26.2.

However, as I said...At the end of the day I’m not overly concerned about how the indexing is performed...at least not until it doesn’t 😂


Airgetlam
  • January 29, 2026

Don’t know…you’d need to ask a coder, which is essentially impossible. I do think (and since I’m not a coder, take it with a generous portion of salt)that it would be harder to choose a better WiFi connection, since that could change at any moment, given the nature of network in general, and certainly WiFi specifically. I just don’t really know how it ‘chooses’ which device to use. It could be the first device in some list, or it could be some other method. 

I don’t think ​@Ian_S is saying that his Era 300s won’t play the data, just that he’s having trouble with that device being the one that creates the file that is shared. 

I use my Era 300s as surrounds, and have never included that Arc in a group that plays my local (NAS) files, so I’m not a good test case to have that discussion with. And my library currently doesn’t change frequently, although I have it auto-updating nightly. No trouble that I’ve noticed, but I can’t gainsay the other thread, which is why I’ve not contributed to the discussion. 


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  • Prodigy III
  • January 29, 2026

 So I would like to understand indexing better than I do now.  My Associated Product is a Beam.  That’s one of five rooms.  When the library indexes is it indexing only to the Beam and the other speakers look to the Beam to see the library?

 I purchased a new 300 a month or so ago.  It refused to play my indexed library.  So I sent it back to Amazon.  So as Ian_S suggests if I had unplugged every room except the new 300 then the 300 would have become the Associated Product and I could attempt an index under those conditions.  Is that correct?

It would have failed. I’m fairly sure your scenario was the same as mine. You had an existing library that was indexed using a NAS name and not an embedded IP. So, when you added the Era 300, it was sent a copy of the index, but just said unable to play file for whatever you put in the queue. If you’d powered off everything but the Era 300, and then asked it to re-index that would also have failed because it can’t cope with the NAS name. If you then tried to add anything, if you have a Synology NAS, that would fail too unless the Sonos account used to connect to the NAS had admin rights. If you did that, deleted your existing share (scary for many), re-added with an IP address, *then* it would have worked… 

Alternatively, just re-adding the share with an IP address instead of name with something other than the 300 as the AP would also have worked. The 300 would then have been able to resolve the location of files put in its queue. The other way to make the 300 play local music would be start playing on an existing device and add the 300 to it as a group. In this scenario the first speaker in the group accesses the NAS and then sends the info over the network in a multicast group to other speakers in the group so it can get the timing sync’d…