Last option to try. Can you check to see if the value has changed in the registry?
On the keyboard, press: Windows + R - In the Run box type: regedit
Go to:
HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\LanmanWorkstation\
AllowInsecureGuestAuth
To set the value without using Group Policy, set the following DWORD registry value to 1 (insecure guest auth enabled) or 0 (insecure guest auth disabled):
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters
AllowInsecureGuestAuth
To set the value without using Group Policy, set the following DWORD registry value to 1 (insecure guest auth enabled) or 0 (insecure guest auth disabled):