Open Registry Editor.
Navigate to Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\LanmanWorkstation.
If the key does not exist, create it by right-clicking on Windows, selecting New > Key, and naming it LanmanWorkstation.
Right-click on LanmanWorkstation, select New > DWORD (32-bit) Value, and name it AllowInsecureGuestAuth.
Double-click on it, set the Value data to 1, and press Enter.