Unable to access Drobo SMB after updating Windows 10.
Open Windows Features, check SMB 1.0.
https://support.microsoft.com/en-nz/help/4034314/smbv1-is-not-installed-by-default-in-windows
Fix 2
Unable to Access Drobo on Windows 10
If you want to enable insecure guest access, you can configure the following Group Policy settings:
Computer configuration\administrative templates\network\Lanman Workstation
"Enable insecure guest logons"