Have you checked the Buffalo’s setting for SMB to make sure that a firmware update didn’t turn off SMB v1 and NTML1?  Since the Sonos speakers use a different method to reach the NAS, the fact that a desktop machine can ‘see’ the music doesn’t really impact whether Sonos can. 
 

Its been a semi-frequent issue when a firmware update alters the settings on an NAS, at least on my Western Digital, without notification. Certainly worth double checking, as it completely fits your situation. 

Thank you for your reply and suggestion. I just double-checked the settings and the SMB setting is still on. (It says, under protocol: “Switch between SMB2 and SMB1 automatically.” I am, admittedly, only vaguely aware of these types of things, so I will be honest: I don’t see any mention of NTML anywhere, but AFP is listed as on/active as well. 

I too have had the exact same problem with media files stored on the Buffalo NAS. SMB settings remain unchanged - switch between SMB2 and SMB1 automatically and this issue only occurred after recently applying the update to the Sonos controller. 

Note that if I add smaller subfolders containing music media these will occasionally add successfully but will eventually revert to the error message stated above. The same behavior is seen from Sonos controllers on IOS and Windows hosts. 

What did Sonos say when you submitted a diagnostic and called in?

Yet to get through here - will attempt to get hold of a real person tomorrow. Have you managed to log anything yourself?  

hi @skilletP in analogy with a Synology NAS, Sonos requires SMBv1 enabled and needs the NTLMv1 protocol to authenticate

Update: After spending over an hour on the phone with Sonos (they were very helpful and courteous -- I have only good things to say about the customer support), ultimately, it turned out that some settings related to shared access had somehow gotten turned off. It was unclear whether that was due to the update itself or possibly due to a MacOS update that was run a week or two earlier. The error message (discussed above) didn’t indicate anything like that, so it took quite a lot of trial and error to get to the source of the issue. But, ultimately, it was resolved and I have music back. 

thanks for sharing the good news @skilletP  - enjoy

Hi @skilletP , I seem to have the same problem as you - happened about a week ago.

Do you have any more information as to how it was fixed! I am pulling my hair out here! 

Thanks!

Exact same problem. Same NAS. Tried all weekend to get it to work. This evening, I switched the SMB to SMBv1, not automatic. Everything appears to work now.

I may have found an issue with SMB on the buffalo Linkstation LS710D0201. But first, I need to express my pure joy that skilletP was able to fix his problem however, “a lot of trial and error to get to the source of the issue”??… Not helpful to anyone ever. Please if you find a solution or just a work around, or things you tried that did not work, please share.

Using the NAS navigator2 if you open settings. and select File Sharing. then SMB (gear), select edit. It appears the default is Auto. Switch this to Manual.  I was then able to use the NAS Navigator2, double click on the drive, windows file manager pops allowing me to navigate to my music. Then click on the directory link above and copy, my looks like this: \\LS710D864\share\SonosMusic.  Go to Sonos music library settings and add.

My troubleshooting started with changing to Manual and selecting SMB1 only (That Worked). Then I did SMB1 to SMB2.1 (That Worked). Then I did SMB1 to SMB3.1.1 (That Worked). Then I switched back to Auto, That did not work.  Not sure why Auto is causing an issue, or what other problems may show up by not using Auto.  However it is now working for Sonos.

Thank you for sharing, Jeff_123.  Much the same thing happened to my SONOS Port and Buffalo Link Station.  After a long journey I finally found this thread.  The default setting was “Both SMB1 and SMB2”(in Japanese version).  I changed it to “SMB1 only”(That worked).  And then I changed it again to “SMB2 only”(That worked), although there is no SMB3 (or later) option on my menu.  I still don’t know what the real problem is, but it is now working.  I’m thankful my entire 500GB music library is OK!

I wish to just reaffirm my experience also re LinkStation LS210D and Sonos refusal to index or unable to find library on my Windows 10 (XPS) network. Bottom line: default LS setting (switch automatically between SMB1 and SMB2) seemed to be the culprit. I spent hours with Sonos tech support (my tech a C-) and then, when Sonos said had to be a Buffalo NAS support issue, and then with Buffalo tech support (my tech an A+). 

After normal setup of the device, I did make its ip a static one. I set up \\LS210D2name]\Music folder with no access restrictions (a public folder), and copied my collection of ripped folders with music. (I had a bunch of CD’s ripped five years ago at divorce and that service placed a .jpg cover in the folders.) But the default SMB setting was auto switching between SMB1 and SMB2. As an aside, although I could directly map and access my audio files using Windows 10 explorer and even play my music using Windows player. I disabled Firewall | Auto-Protect, etc. , I got various Sonos error messages (Music Files No Longer Available, etc. and could not index the library. I read THIS thread and voila!

My steps included of course changing the SMB setting to SMB1 only, then rebooting the computer. (Then for good measure, turning the NAS device on and then rebooting. Rebooting my router. And, double checking I had access to the shared drives on the NAV from my network.)

I read above some then set the SMB setting to SMB2 only.  A bit reluctant to mess with. If anyone knows that is a seamless next step and there is value in having the lattter setting, please advise below.

Best!

It’s unfortunately not uncommon for firmware updates to various routers to turn off SMBv1 access, without telling the user specifically. The intention is greater security for your data, certainly, not malice, but for users of Sonos S1, it’s problematic, and, as you found out, something that takes time to figure out. 

Happened to me on a Western Digital NAS update, too, I feel your pain. I’ve moved to Sonos S2 OS on all my devices at this point. S2 allows SMB v2 and SMB v3. 

Airgetlam, I can enable SMBv2. Should I since I am on S2? The issue is the Linkstation 3rd option of auto switching. I am now on SMBv1 but could set to SMBv2 if there were any benefits.

Yes, as I said, in the last sentence of my post, S2 supports both SMB v2 and SMB v3. If you can, you should, in my opinion. While there’s not yet a huge difference between the two systems, S2 does help you there, for sure. 

Overall, S2 is very docile with respect to SMB V1-2-3. I’ve been able to switch my drive SMB level while music is playing and SONOS didn’t seem to care.

Thanks Guys - had the same problem from Monday. Nio clue what any of the acronyms mean but this resolved it.