When dealing with mixed Windows environments accessing Samba shares, Windows 7 often presents unique authentication challenges. The scenario where XP/Vista machines successfully authenticate while Windows 7 fails with "The specified network password is not correct" typically points to protocol negotiation issues.

Windows 7 by default uses NTLMv2 authentication, which may conflict with older Samba configurations. First, verify the Samba server's supported protocols:

# On Linux Samba server
testparm -s | grep "ntlm auth"

For Windows 7, check the local security policy settings that affect SMB:

# PowerShell command to check current settings
Get-ItemProperty "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa" | 
Select-Object LmCompatibilityLevel

Try these solutions in order of preference:

Option 1: Modify Windows 7 Registry

Create a .reg file with these contents:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa]
"LmCompatibilityLevel"=dword:00000001

Option 2: Samba Configuration Adjustment

If you can access smb.conf, add these parameters:

[global]
client ntlmv2 auth = yes
client use spnego = no

Option 3: Alternative Connection Methods

Try mounting with explicit protocol specification:

net use Z: \\192.168.0.20\Smd /user:username password /persistent:yes /savecred

When basic fixes fail, collect these diagnostic outputs:

From Windows 7 (Command Prompt):

nltest /sc_query:ADDONICS_NAS

Packet capture analysis (requires Wireshark):

Filter: smb || nbns || nbss

• Ensure consistent time synchronization (NTP)
• Standardize credential formats (DOMAIN\user vs. user@domain)
• Document exact SMB protocol versions supported

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When dealing with NAS devices running Samba services, we often encounter authentication inconsistencies across Windows versions. Here's what's particularly puzzling:

# Working on Windows XP/Vista
net use l: \\192.168.0.20\Smd /user:username password

# Failing on Windows 7 (same credentials)
System error 86 has occurred: The specified network password is not correct

Windows 7 introduced stricter security defaults that can break compatibility with older SMB implementations:

• SMB2 as default protocol (instead of SMB1)
• NTLMv2 requirement (instead of LM/NTLM)
• Different password encryption hashing

For NAS devices that can't update their Samba implementation, we can modify Windows 7's security policy:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa]
"LmCompatibilityLevel"=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0]
"NtlmMinClientSec"=dword:00000000
"RestrictSendingNTLMTraffic"=dword:00000000

Save as smbfix.reg and merge, then restart the computer.

Instead of net use, try these PowerShell alternatives:

# Method 1: Explicit credential object
$cred = New-Object System.Management.Automation.PSCredential("username", (ConvertTo-SecureString "password" -AsPlainText -Force))
New-PSDrive -Name "L" -PSProvider "FileSystem" -Root "\\192.168.0.20\Smd" -Credential $cred -Persist

# Method 2: Using cmdkey to store credentials first
cmdkey /add:192.168.0.20 /user:username /pass:password
net use l: \\192.168.0.20\Smd

Verify these Windows 7 network settings:

1. Ensure "Network Discovery" is turned on in Network and Sharing Center
2. Check that the workgroup name matches your NAS workgroup
3. Disable IPv6 if not needed (some NAS devices have issues with it)

If you have access to the Samba config (smb.conf), add these parameters:

[global]
    client min protocol = NT1
    server min protocol = NT1
    ntlm auth = yes
    lanman auth = yes

When all else fails, capture network traffic to identify the authentication failure point:

# Capture filter for SMB traffic
wireshark -i "Ethernet" -f "port 445 and host 192.168.0.20" -w smb_capture.pcapng

# Look specifically for Session Setup AndX requests and responses
# Pay attention to NTLMSSP negotiation packets

Common packet analysis findings include mismatched protocol versions or rejected authentication tokens.