I installed a clean version of Windows 10 after successfully upgrading from Windows 8.  However, now I can't access my QNAP NAS.

It doesn't automatically show up in File Explorer, however if I type in the address of the NAS, I can see the folders of the NAS.  I can also ping the NAS address successfully.  However, when I try to open a folder on the NAS, it asks for login credentials.  I typed in the login details that I use for the NAS, but it gives me an error - \\server is not accessible.  You might not have permission to access this network resource.  Contact the administrator of the server to find out if you have access permissions.  It seems like it doesn't recognise my login.

Things I've tried/checked:

1. My login details for the NAS - working when I login via the QNAP Turbo System.
2. I checked the permissions of my account on the NAS, and it has full access.
3. Checking the Workgroup name - both the NAS and Windows showing the same name.
4. Windows networking set to Private/Home, and firewall on default dettings.
5. Access on another computer - my wife's Windows 8.1 machine can still access the folders of the NAS as normal.
6. Turning off and on the Microsoft Networking service on the NAS, and rebooting both NAS and my PC - no change.
7. Creating a new login for the NAS and using that to access the folders of the NAS on my PC - no difference.
8. Updated the firmware of the NAS - no change.

I've tried googling, and tried (above) some of those things, but nothing else seems to be suggested.  I can't think of anything else to try, other than resetting the NAS to factory settings, but I'm reluctant to do that because it was working fine on Windows 8, suggesting that something about Windows 10 isn't configured correctly.

Anyone care to walk me through what I should be doing next?