After latest Win 11 update 24H2, system refuses to connect to my NAS ,how to resolve this?

The problem you're experiencing is likely due to new security features in Windows 11 24H2, such as SMB signing and guest fallback protection. Here are some steps you can try to resolve this:

Method 1: Disable SMB Client Signing Requirement

1. Open Local Group Policy Editor: Press Win + R, type gpedit.msc, and press Enter.
2. Navigate to Security Settings: Go to Computer Configuration>Windows Settings>Security Settings>Local Policies>Security Options.
3. Disable SMB Signing: Find Microsoft network client: Digitally sign communications (always) and set it to Disabled.
4. Apply Changes: Click Apply and OK, then restart your computer.

Method 2: Enable SMBv1 Protocol

1. Open Windows Features: Press Win + S, type "Windows Features", and open Turn Windows features on or off.
2. Enable SMB 1.0/CIFS File Sharing Support: Check the box for SMB 1.0/CIFS File Sharing Support and click OK.
3. Restart Your PC: Restart your computer to apply the changes.

Method 3: Update NAS Credentials

1. Open Credential Manager: Press Win + S, type "Credential Manager", and open it.
2. Remove Old Credentials: Under Windows Credentials, find your NAS credentials and remove them.
3. Add New Credentials: Re-add the correct username and password for your NAS.

Method 4: Check Network Discovery and Firewall Settings

1. Enable Network Discovery: Go to Control Panel>Network and Sharing Center>Change advanced sharing settings. Turn on network discovery and file and printer sharing.
2. Configure Windows Firewall: Go to Settings>Privacy & Security>Windows Security>Firewall & network protection. Ensure that file-sharing protocols are allowed