"Authentication failed because NTLM authentication has been disabled" Cannot connect to Synology NAS drives. Multiple fixes attempted.

Question

Problem:

I updated my PC from 23H2 to Windows Pro 24H2 and can no longer see my Synology NAS or access the pre-mapped network drives. Attempts to remap the drives fail, “Authentication failed because NTLM authentication has been disabled.” This is my third time trying to fix this problem after rolling back to 23H2 on the previous attempts before the 10-day limit expired.

Platforms:

Dell OptiPlex 7060 MT (refurb), i7-8700, 32GB of DDR4-2666, Samsung EVO 970 Plus M.2 500 GB.

Windows 11 Pro 24H2, Build 26100.3037, Windows Feature Experience Pack 1000.26100.48.0, with all current updates as of 02/09/2025.

AV/Firewall is Microsoft Security (Defender) only.

Synology DS1522+ NAS running current OS (DSM 7.2.2-72806 Update 3) with all current updates as of 02/09/2025.

Repair sequence tried (this time):

1. Synology recommended disable “BlockNTLM”.

I ran the PowerShell command ”Set-SMbClientConfiguration -BlockNTLM $false”.

I used the PowerShell command “Get-SmbClientConfiguration” to verify BlockNTLM is set to false.

I looked at the Group Policy and verified “BlockNTLM” is set to “not configured”.

I still could not see the NAS in Windows File Explorer or connect to the pre-mapped drives. (“This connection has not been restored.”)

I rebooted PC. No change.

2. Disable firewalls.

I turned off all Windows Security (Defender) firewalls. No change.

3. Microsoft recommended Enable Guest Logon.

I implemented PowerShell command “Set-SmbClientConfiguration -EnableInsecureGuestLogons $true” and verified it with the above “Get” command.

I still could not see the NAS in Windows File Explorer or connect to the pre-mapped drives.

I rebooted PC. No change.

I tried to remap the NAS drives using IP address, entered my credentials, and again got the familiar “Authentication failed because NTLM authentication has been disabled” response.

4. Look for problems with Synology NAS SMB settings.

I have tried every combination I can think of in the Synology SMB advanced settings screen.

I still could not see the NAS in Windows File Explorer or connect to the pre-mapped drives.

[I returned SMB settings best I could to default.]

5. Synology recommended “LAN Manager Authentication” change.

I changed Group Policy setting "Network Security: LAN Manager Authentication Level" from “not defined” to "Send LM and NTLM Responses".

I still could not see the NAS in Windows File Explorer or connect to the pre-mapped drives.

Attempts to remap the NAS drives using IP address (entering my credentials) still get the familiar “Authentication failed because NTLM authentication has been disabled” response.

I rebooted both the PC & NAS. No change.

[I reactivated the firewalls.]

I am sooooooo sick of this problem. Please help.

Answer 1

What did you mean by "Then I changed group name."?

Answer 2

Well, this explains it. I, too, had Windows 2012 R2, and the client connected to this computer.

So, all I need to do is find the Server 2016 client connector and run it.

Do you have a copy of it? I don't know if I have it.

Answer 3

Aside from file storage, I use my NAS for automated PC backups. Does anyone know if reinstalling the Windows Server connector interferes with Active Backup for Business Client connector and its function to aid nightly PC backups?

Update:

I updated my Win 11 Pro PC to 24H2 again and reinstalled the Microsoft Server Connector file (WSE Client 64-bit) a few days ago. [Rebooted.]

The mapped NAS drives were still unreachable. However, I was able to disconnect and map the drives from scratch to make them accessible.

I still cannot see the other computers on network or the NAS drives, but that may just be something funky with my computer. I can probably live with it.

The WSE connector software is NOT interfering with Active Backup for Business application. It works fine.

Answer 4

Thank you so much! Reinstalling the Client connector worked also for me! Luckily I had retained a copy, since my Windows Server was retired a year ago. The filename of the installer is WSEClient-x64.msi .

Answer 5

THANK YOU!!

There must be something that the WSE Client had configured when it was previously installed that gets broken by the 24h2 update, because re-installing the client fixed my machine too!

I had to delete and re-add a saved credential in credential manager but after that I was able to access my Unraid NAS again!