honestly, I doubt you will find a solution for this issue. At first the setting seems to be more related to local configuration instead of server (UCS) side (unsure here, indeed). Second, it the kb article refers to totally outdated Windows versions (2000, 2003, XP) which tells me there seems to be not such parameter (or at least no such an issue) on more recent Windows releases and therefore I additionally doubt there is such a parameter in Samba.
So I would do as advised: ask Sonos support for proper solution.
The corresponding UCR variables to check are samba/min/protocol which defines the minimum protocol version the server will speak with the client and samba/ntlm/auth which defines the oldest authentication method the server will allow. My guess is that samba/ntlm/auth is the culprit here as that was changed last year to only allow NTLMv2. My guess is that Sonos not only speaks the old SMB 1 protocol but only uses the NTLMv1 authentication.
samba/min/protocol being unset shouldn’t be a problem as the defaults will result in LANMAN1, which is the oldest possible anyway.
But samba/ntlm/auth being unset means that NTLMv2 will be required. Try setting that variable to ntlmv1-permitted (and restarting Samba afterwards).
Just an additional note: SMBv1 is really, really, REALLY outdated and it is strongly recommended to leave it disabled for security purposes.
You might want to read this article (German only).
