Investigate an SMB Signing Error Before Weakening Windows Share Security
A shared folder that worked on an older computer can fail on a newer one because its authentication or signing arrangement no longer meets the client's requirements. The exact error matters more than a general description such as NAS not working.
Record the Windows version and edition, the NAS or server model, the share name and the complete error. Keep usernames private and leave passwords out of screenshots. Confirm with the server owner whether the share expects an individual account or guest access.
Check the requirement, not just the network connection
Microsoft documents that Windows 11 24H2 Pro, Enterprise and Education require inbound and outbound SMB signing by default. Its 24H2 Home edition does not require either by default. An organisation can impose its own configuration, so edition is a starting point rather than proof of the current policy.
In PowerShell, this read-only command displays the client's signing requirement:
Get-SmbClientConfiguration | Format-List RequireSecuritySignatureTrue means the client requires signing. Preserve the result with the failure message. Signing helps detect altered SMB traffic; requiring it is incompatible with guest access. Microsoft identifies STATUS_INVALID_SIGNATURE as one possible symptom when a third-party server cannot provide the required signing.
Do not interpret a successful ping or visible server icon as proof that this security negotiation succeeded. They answer different questions.
Resolve the server arrangement deliberately
Ask the authorised server administrator to check its supported signing settings and named-account access. Microsoft recommends enabling signing on the third-party server and discourages disabling client signing as a workaround. Use the server vendor's instructions for that exact software version.
After an approved adjustment, reconnect to the intended share with the expected account. Open a harmless known file; if writing is part of the job, create and reopen an agreed disposable test file in an authorised folder. Verify folder permissions separately from connection success.
If the server cannot meet the requirement, document that compatibility limit for a replacement or migration decision. Rebuilding a RAID array or clearing every saved credential does not address an SMB signing mismatch.
Sources: Microsoft SMB signing behaviour.