1. Run Registry Editor (REGEDIT).
  2. Navigate to the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters

  3. Name the new value as AllowInsecureGuestAuth and set its value data to 1.

or:

c:\windows\system32> set-smbserverconfiguration -enablesmb2protocol $false