When trying to access an SMB share running on openmediavault you may get some of the following error messages, even though permissions have been set up correctly on the server and the correct password is being provided by the client:
Attempting to access the root of the server \\x.x.x.x\ you receive:
You do not have permission to access \\x.x.x.x\. Contact your network administrator to request access.
Attempting to access a specific share on the same server \\x.x.x.x\share you receive the following after providing the username and password:
The specified network password is not correct.
The problem was due to a bad Group Policy setting. Using gpedit.msc, navigate to the following:
Network security: LAN Manager authentication level
In this case it was set to:
Send LM & NTLM – use NTLMv2 session security if negotiated
To fix the problem it was changed:
Send NTLMv2 response only
This is the default setting for Windows Server 2008 R2 and later. The change is immediate and no reboot is required for it to take effect.