When you try to access to a consumer or old NAS with your brand new Windows 10 Fall Creators Update you will face a network access error.
Due to security issue in SMB protocol, the new Windows 10 and Windows Server 2016 release 1709 start with some SMB feature disabled by default:
- SMBv1 not installed (enable it with Enable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol)
- SMBv2 Guest Access disabled
As Microsoft state:
In Windows 10 Fall Creators Update and Windows Server version 1709, the SMB2 client no longer allows the following actions:
- Guest account access to a remote server
- Fallback to the Guest account after invalid credentials are provided