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Fix CasaOS Shared Folder Access on Windows 11 24H2

A CasaOS user could access the same shares from a Mac and an older Windows 11 laptop, but a new Windows 11 24H2 PC returned an extended error. The author traced it to Microsoft's new SMB signing and guest-access security defaults.

If a CasaOS shared folder works from a Mac and an older Windows computer but a new Windows 11 24H2 PC returns an extended error, the CasaOS share itself may not be broken. The December 2024 IceWhale Community post traced this exact pattern to security changes Microsoft introduced in Windows 11 24H2.

Windows 11 24H2 tightened SMB behavior in ways that affect home NAS devices: SMB signing is required by default on Pro, Enterprise, and Education editions, and insecure guest fallback is disabled on Windows 11 Pro. Microsoft recommends fixing the NAS side first—use SMB signing and authenticated usernames/passwords—rather than weakening the Windows client.

Why the Old Windows PC Works but the New One Fails

The original CasaOS user already had a Mac and an older Windows 11 laptop accessing the same shares successfully. Only the replacement Windows 11 system failed. That makes the Windows build and its SMB policy a more useful troubleshooting target than the disk or share itself.

Microsoft's Windows 11 24H2 NAS guidance explains that the release requires SMB signing by default on several editions and disables insecure guest fallback on Pro.

What SMB Signing Changes

SMB signing lets the client and server verify that network messages were not altered in transit. Microsoft's current SMB signing documentation says Windows 11 24H2 Pro, Enterprise, and Education require inbound and outbound signing by default.

If a third-party SMB server does not support the required signing behavior, Windows can reject the connection even though older computers still work.

Why Enabling Guest Access May Still Not Work

The community author had already enabled insecure guest access, but required signing and guest access do not combine cleanly. Microsoft notes that requiring SMB signing also blocks normal guest fallback.

The safer long-term configuration is:

  1. Use SMB2/SMB3 rather than SMB1.
  2. Create a real Samba username and password.
  3. Enable SMB signing on the server when supported.
  4. Connect from Windows using authenticated credentials.

Use the IP Address as a Diagnostic

The first community reply suggested testing the server IP instead of its host name:

\\192.168.1.50\ShareName

This is useful for separating name-resolution problems from SMB authentication or signing problems. For a permanent signed environment, Microsoft's current guidance prefers correctly resolved host names rather than using raw IP addresses as the design goal.

Do Not Enable Every SMB Version as the First Fix

Another community suggestion was to install all SMB protocol versions in Windows Features. That is not the preferred current approach. SMB1 is obsolete and disabled by default on modern Windows systems. A current CasaOS/Samba deployment should normally use SMB2 or SMB3.

Do not enable SMB1 merely because Windows 11 24H2 fails to connect. First investigate signing and authenticated access.

  1. Enable SMB signing on the NAS/server if possible.
  2. Disable guest-only access.
  3. Create a username and password on the NAS.
  4. Update the NAS/server software if newer SMB support is available.
  5. Only after those options fail, consider weakening Windows signing or guest policies.

Check the Windows SMB Client Settings

From an elevated PowerShell window:

Get-SmbClientConfiguration | Select RequireSecuritySignature, EnableInsecureGuestLogons

This lets you see the current client policy before changing anything.

Last Resort: Disable the Signing Requirement

Microsoft documents this compatibility command:

Set-SmbClientConfiguration -RequireSecuritySignature $false

Windows asks for confirmation. This reduces SMB security, so do not make it the first CasaOS fix. Microsoft explicitly recommends correcting the third-party server when possible.

Last Resort: Re-Enable Insecure Guest Logons

Set-SmbClientConfiguration -EnableInsecureGuestLogons $true

This can help with a guest-only server, but it weakens authentication. If signing is still required, enabling guest access alone may not solve the connection.

Clear Stale Windows Credentials

After moving from guest access to a named Samba account, Windows may keep an old SMB session. Disconnect existing mappings:

net use * /delete

Then remove obsolete entries from Credential Manager > Windows Credentials and reconnect with the intended account. This command disconnects all current mapped network shares for the user, so use it deliberately.

Can FileZilla Replace SMB?

A later community reply asked about FileZilla. FileZilla normally uses FTP, FTPS, or SFTP; it does not replace a Windows Explorer SMB share by itself. If SSH/SFTP is configured on the server, it can provide file transfer, but it uses a different protocol and permission model.

CasaOS Shared Folder Troubleshooting Checklist

  1. Confirm the same share still works from another client.
  2. Confirm the failing computer is Windows 11 24H2 or later.
  3. Test both host name and LAN IP.
  4. Do not enable SMB1 as the first troubleshooting step.
  5. Prefer a real Samba username/password instead of guest-only access.
  6. Check whether the Samba server supports signing.
  7. Inspect Windows with Get-SmbClientConfiguration.
  8. Clear stale sessions and cached credentials after changing authentication.
  9. Use Microsoft's insecure compatibility switches only when the server cannot be corrected.

CasaOS Shared Folder on Windows 11 FAQ

Why did the share stop working only on Windows 11 24H2?

Windows 11 24H2 introduced stricter default SMB signing and guest-authentication behavior. The original community author traced the failure to those Microsoft changes.

What does “an extended error has occurred” mean?

It is a generic Windows network error. In this source thread, the author found that Windows 11 24H2 SMB policy changes were the relevant cause.

Should I enable SMB1?

Not for a normal modern CasaOS deployment. Fix SMB2/SMB3 signing and authenticated access first.

Is disabling SMB signing safe?

It removes a protection against tampering and relay attacks. Microsoft documents the switch for incompatible third-party servers but recommends fixing the server where possible.

Can I keep using a guest-only share?

Windows can be configured to allow insecure guest logons, but Windows 11 24H2 intentionally discourages that model. A named SMB account is safer.