SKDavis

Windows updates, like 24H2, can negatively affect existing NAS installations. The last update on my Windows 11 PC disconnected mapped drives after performing a reboot. The instructions posted earlier worked for the first NAS but when a second NAS was added, it did not work correctly responding with "Access is denied" when the login window appeared. The updated instructions below DO NOT require using ESET to override the Windows filewall.

SYNOLOGY NAS SETTINGS
To start, log in to your NAS and go to Control Panel > File Services > and click the SMB tab and ensure the following settings are correct.

1. Check the box for Enable SMB service box to enable SMB.
2. The Workgroup name should be the same name used for your PC workgroup.
3. Check the box for Enable the transfer log if you want to track transfer activity in the Synology log file.
4. Check the box for Enable Windows network discovery to allow file access via SMB

 
Then click Advanced Settings to configure SMB. Leave the WINS server line blank unless you are using LAPD and are connecting to a Microsoft server.
For security reasons, DO NOT use SMB1 for the minimum SMB protocol. Windows11 no longer supports SMB1.
Set the Maximum SMB Protocol to SMB3
Set the Minimum SMB Protocol to SMB2 large MTU (using large MTU enables increased throughput and efficiency)

Enable the following to improve caching and improve performance:
Check the box for Enable Opportunistic Locking
Check the box for Enable SMB2 file leasing
Check the box for Enable SMB3 directory leasing
Click the Apply to all shared folders if allowing access to more than the clients home folder.

Then select Clear SMB cache. When finished select save.


 
 
WINDOWS SETTINGS
The remaining instructions allow Windows11 to connect and MAP your NAS drives.
Adjust the Windows11 Client Settings as follows:

1. Open the Windows Run dialog by pressing the Windows Key + R.
2. Type secpol.msc and click Enter to open Local Security Policy (Note: Windows Home editions do not have this feature, but NTLMv2 is the standard for Windows 10 and 11).
3. Navigate to Security Settings > Local Policies > Security Options.
4. Double-click Network security: LAN Manager authentication level.
5. Change the dropdown to Send NTLMv2 response only\ refuse LM & NTLM.
6. Click Apply, OK, and restart your computer.
    
7. Locate Notepad in the start menu, right click and select RUN AS ADMINISTRATOR.
8. Select YES to allow Notepad to make changes.
9. Click File Open and navigate to: C: > Windows > System32 > drivers > etc
10. At the lower right of the notepad page select the pull down menu that displays Text Documents (*.txt)
11. Change it to All Files (*.*)
12. Select hosts and the following file content is loaded.
    
    
    
    
    
13. Scroll to the end of the file and add a new line containing you NAS IP and name:
    
    
    
    
    
14. Change the 192.168.1.21 address to the address assigned to the NAS.
15. Then change my-nas1 to the name you assigned to your NAS.
    If a second NAS is used add another new line with that NAS's IP address and name.

Ensure the NAS has been assigned a reserved IP address on the router. If the NAS does not have a reserved IP address, restarting or rebooting may cause DHCP to assign a different address causing mapped drives to disconnect.

IMPORTANT!!! - Create a firewall rule on the router that blocks WAN (Internet) access to port 445 on the LAN (Local Access Network) to prevent unauthorized remote access to your NAS drives.

These settings allow logging into the the NAS from WIndows. To check the Windows login credentials slick the Windows search box and type in credential manager. Then select Windows Credentials which should display the NAS device(s).

Note: These changes allow Windows to access NAS devices and display their folders in the Windows File Explorer Network window. Drives can be mapped using Windows File Explorer or Synology Assistant.