From here: https://support.microsoft.com/en-gb/help/2957623/cannot-access-shared-files-or-folders-on-a-drive-in-windows-server-201
Symptoms
You may experience one of the following issues:
- You can see the shared files but cannot open them.
- When you open a shared file, the loading progress bar is displayed as zero percent.
- When you open a shared file or a folder, Windows explorer freezes.
- If you try to restart the Server service, the service freezes in the stopping state.
- Microsoft Office Access databases (.mdb files) that are hosted on Windows Server 2012 shares may be corrupted.
- A "file is locked by another user" or "is locked for editing" error occurs in Microsoft Excel.
- SMB2 dialect negotiation receives only a TCP ACK response.
To work around these issues, follow these steps:
- Disable the leasing on the file server. To do this, run the following command:
REG ADD HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parameters /v DisableLeasing /t REG_DWORD /d 1 /f
Note After you set this registry key, SMB2 leases are no longer granted, but oplocks are still available. This setting is primarily used for troubleshooting.
- Restart the file server, or restart the server service. To restart the service, run the following commands:
NET STOP SERVER
NET START SERVER