In the other threads, there has been a solution posted.

However, this change was made by Synology, not Sonos. It feels like your anger is misplaced. Sonos has not altered anything on their side of the equation. 
 

If you could point me to a solution, I’d appreciate that--every post I could find that offered a solution either said to enable SMB1 or enable NTLMv1 authentication.  I have enabled both. 

I disagree about whose fault this is--Sonos has elected not to support their older gear on their newer software platform, and has elected not to continue development on the older software platform they require me to use.  They are the only equipment provider I have that has this problem--every other hardware producer can work with Synology NAS’s.

I’d start with this thread:

@sjw has provided links to other threads inside that thread, as well.

I’m not sure exactly how you expect Sonos to put new software on devices that don’t have the RAM/CPU available to hold that new software. My ‘386 computer with a 512 Meg HD won’t run Windows 11. To whom should that blame be apportioned?

There seem to be a couple of options - one downgrades the updated SMB addon and the other edits the smb.conf file.  Both solutions need a small amount of technical knowledge and accessing your NAS via PUTTY.

The latter option is detailed here.

@sjw: thanks!  Disabling unix extensions did it for me.  (And mad props for walking people through how to use vi)

Yeah, vi 101

Editing SMB.config did unfortunately not do anything for me/my Setup . Have not yet tried downgrading SMB addon but it appears do be considerably more complicated than editing SMB.config.

irrespective of who‘s responsible, my system is currently just useless. If there is no easy fix soon I am going to replace either the NAS or the sound system with another provider. And will not likely go back to the replaced one for the foreseeable future.

Since no other NAS company seems to have the issues I’d change brands there.

My dirt cheap NAS solution, a Raspberry PI and plug-in USB music storage drive has worked flawlessly for years.

Honestly, I’d just upgrade to S2, and if necessary, replace any device that is S1 only. Computers ( which is what Sonos devices are ) do age out. 

The root issue is that SMB1 has problems--it is insecure and very chatty on the network; SMB2 is a far better protocol.  The problem is that Sonos elected not to support SMB2 in their S1 systems, even though the protocol was well-established while they were selling product.  Essentially, Sonos requires your NAS to use an insecure, suboptimal protocol.

All the solutions to this problem involve forcing the Synology NAS to be less secure and to chew up more network bandwidth.  The fact that Synology alone of all the NAS providers has its systems more secure and more efficient by default is evidence that they are doing the job better than their competition, not worse.

Upgrading Sonos gear to S2 is a very expensive remedy, and one that rewards Sonos for doing a poor job engineering their S1 systems, and a worse one in customer service.  SMB2 was released in 2006; Sonos was selling S1 systems long after that (I bought mine in 2013, I believe).  This is not a case of computers aging out, this is a case of a company selling ancient technology and then bailing on it without offering their customers an upgrade path.

I don’t think Sonos ‘elected to not support’ SMB v2, in fact they have supported it, in S2. They were forced by memory limitations in S1 and those devices that run it, to not be able to update the Linux kernel. 
 

I suppose they could have gone the route of invalidating and stopping support and functionality for all S1 devices, but they took the higher road of continuing to support that hardware. I’ve heard that not all companies have done so when they’ve come out with new hardware. 

They designed and sold their S1 systems without SMB2 support, despite its being the current version of the protocol.
As to memory and CPU requirements required to run Linux and SMB2: I run a current version of Ubuntu Linux on VM hosted on a fractional micro-CPU with 600Mb of RAM, and have no problems with SMB2 (or SMB3).  Similarly, SMB2 runs fine on a Raspberry Pi.  There is simply no way memory or CPU is the issue.

And I cannot see where not deleting their app is “taking the high road.”  It’s not like they’ve kept it upgraded with necessary security fixes (like, oh, supporting SMB2).

You may be happy to do business with companies who treat you like that, but I certainly am not.

Have you actually looked to see how much memory the older Sonos devices offer?