Samba 3.6 , SMB2, passwordless access

We had a setup with Samba 3.0 on RHEL5, defining two shares that users could connect to, passwordless, from their Windows workstations. Then their workstations were upgraded to Win10 and now they need to access per SMB2 or SMB3. I upgraded the Samba from 3.0 (which cannot do SMB2 at all) to 3.6 (which can do SMB2 but not SMB3).
But I find I still cannot do passwordless access: this requires seting "security=share" and I understand that is incompatible with SMB2.

• Am I right that only Samba 3.6 will serve, because higher releases are not available for RHEL5.11 and lower releases cannot do SMB2?

• Would there be a way to force a Win10 to use SMB1?

• How can I set up SMB2 to grant passwordless i.e. "guest" access? Example smb.conf, anyone?

(PS do not ask for the original smb.conf, company policy keeps me from publishing it)