Synology NAS music library folder - only works with admin account

I’m a bit curious, since this sounds like a Synology implementation issue, if someone has contacted Synology’s CS to report / ask about it? I wouldn’t think Sonos ‘knows’ what’s at the other end of their data request. 

I'm curious too, why you think it's a Synology implementation issue?

I'd say if there was an issue with Synology where you needed Admin access to a Share in Read only mode, they'd have definitely been aware and resolved it.

Far more likely is there's a Sonos issue that doesn't view the contents without Admin access?

I have perfect access with a Sonos account with read only access to the share.

Users could map a drive to the Share on a PC for example using the Sonos details.  I would bet the contents are viewed perfectly.

We've heard strange things previously with access not working consistently from Sonos and needing to use IP address etc. for access. 

Because it’s only being reported with Synology, and not other SMB accessed drives? My imagination suggests Sonos is making a standard SMB coded request for data to access. The fact that it is being rejected, and only with Synology drives, suggests an issue on the other side, to me. I can’t imagine there’s a bit in the Sonos code that says ‘if the drive is Synology, then do this’. I’d think the Sonos code is merely making a standard request, and has no physical knowledge about what it is connecting to. 
 

Dunno. I haven’t seen any ‘official’ data from Sonos, I was wondering if there was any response from Synology. If it is truly an issue on Sonos’ side, that will be interesting to me, but right now, given the data in this thread, I’m not sure it is. 

My simple SMB / Samba,  Linux based, NAS is showing no issues with Sonos access.

By the same logic, Synology surely just receives some credentials and the Share name and either allows or otherwise?  i.e. although you “can’t imagine there’s a bit in the Sonos code that says ‘if the drive is Synology, then do this”, you totally can “imagine there’s a bit in the Synology code that says ‘if the requester is Sonos, then do (or don’t...) do this”?  But those same credentials are fine accessing the NAS/share from all other devices?
My guess is it’s possibly related to a couple of things - and may depend on how the files got there in the first place.

Sonos could be requesting an elevated access to the files or the root volumes.  Maybe it tries to lock files to read the ID3 tags?  Maybe it’s trying to traverse folders?

I think Sonos has changed something (maybe in the SMB 3 implementation?) where it no longer copes consistently well with NetBIOS names - maybe try using the IP address instead.

Ensure the Sonos user has been Allowed access to SMB Files Service.

Ensure the Sonos user has access to the actual files.  Select the Share - Properties - Permissions and select the Sonos user, click Edit, and set permissions to Read.  Make sure to "Apply to this folder, sub-folders and files".  That should fix issues with linux/ACL mismatches (especially if the files were copied there by Admin).

Can the user connect to the Share and view its conents as the same account from a PC?  If so, it suggests Sonos needs a little more than ‘basic’ read access.  I’d try this first.

Yeah, my Synology NAS is showing no issues with Sonos access either - but it’s running an older firmware.

As I said, I don’t know. What I’m looking for is both sides of the equation, so I can make a more reasoned understanding of the situation. Obviously, I’m not able to fix it. And it could be possible what you’re suggesting is true, I still don’t know. 
 

You state your Synology NAS isn’t having issues with your Sonos system, which is great…but which is running older firmware, the Sonos or the Synology?

I’m running the current Synology firmware, DSM 7.3.2-86009 Update 4. My Sonos user has read-only access to the Music share. It works. I can’t tell you why it doesn’t work for others. But it must have to do with access permission and/or file permissions. But Sonos does not need more than read-only access to an SMB share. That is provided the permissions on the share are correct for that user’s read-only access. As sjw mentioned, this can be easily tested by mounting the share with read-only user credentials and see what you can access.

Edit: If I had to guess:

The Sonos.

So, I added a few more files to the NAS music share location (by dragging a folder with some MP3s in it from my c: to the music share through the synology browser interface).  The library in the Sonos has not updated automatically overnight (2am I think is the default?) to captured them.  I pressed the ‘scan for new content’ button this morning (from latest iPhone S2 app), I hear the NAS spool up and got a scan complete message.  I then checked the library from the iPhone app and the new songs are not visible.  I’ve just mapped the music share to my windows PC using the Sonos user (read-only) account - it maps, I can see files, play files, and can’t delete - all as it should be then.  I went back to the iPhone app and ‘scan for new content’ again - this time I get the message “//NAS/folder is no longer available” I was seeing before.  But the existing library remains selectable in the IPhone app as a source, and plays the tracks of what it ‘knows’ already - so back to my thought of seemingly not indexing (or similar) properly unless it’s an admin account??

I’m just going move all my music over now (after a bit of MP3tag tidy up), give my Sonos user account full admin rights, scan the share folder again, then switch back to read-only then leave it.  I won’t be adding any more files, so I’ll be happy to not touch it again at that point.  It doesn’t really fix the issue but it’s enough for me now (until the next s/w update from either side blows it up 😂).

Thanks everyone. 👍🏻

The spin-up time on a NAS can be an issue, mine (a while back) was slow with a "green" drive and caused issues. Now using an SSD as music storage so no spin-up delay.

You might try spinning up the  NAS drives before accessing with Sonos to see if that chqnges things.