Connection to NAS Server with Read/Write Check. Impersonation Fails

I'am working on a program which has to check if there is a connection to the NAS and if it's possible to write and read data from it. Checking the connection is not a problem.

I'am running on a Windows Server 2012 and know the credentials from the NAS. I tried impersonating with those credentials but this did not work. I'am always getting the same error. The user name or password is incorrect. But when I connection with the windows explorer with the same credentials it works.

This is my DLL Import and the necessary variables

[DllImport("advapi32.dll", SetLastError = true)]
    public static extern bool LogonUser(String lpszUsername, String lpszDomain,
    String lpszPassword, int dwLogonType, int dwLogonProvider, ref IntPtr phToken);

// Variables
private IntPtr m_Token;
private WindowsImpersonationContext m_Context = null;
private string m_Domain;
private string m_Password;
private string m_Username;

m_Domain is different to the local domain

This is the actual Impersonation

            m_Token = IntPtr.Zero;
            bool logonSuccessfull = LogonUser(
               m_Username,
               m_Domain,
               m_Password,
               (int)LOGON32_TYPE_NETWORK,
               (int)LOGON32_PROVIDER_WINNT50,
               ref m_Token);
            if (logonSuccessfull == false)
            {
                int error = Marshal.GetLastWin32Error();
                throw new Win32Exception(error);
            }
            WindowsIdentity identity = new WindowsIdentity(m_Token);
            m_Context = identity.Impersonate();

LOGON32_TYPE_NETWORK is equal to 3, LOGON32_PROVIDER_WINNT50 is equal to 3

This code is executed with administrator rights.

This is the error which gets thrown:

System.ComponentModel.Win32Exception (0x80004005): The user name or password is incorrect

This error get's thrown at

if (logonSuccessfull == false)
{
     int error = Marshal.GetLastWin32Error();
     throw new Win32Exception(error);
}

Is there another way? Or do have to use other LogonType's or LogonProvider?

These I have also tried but also did not work for me.

private const int LOGON32_PROVIDER_DEFAULT = 0;
private const int LOGON32_LOGON_INTERACTIVE = 2;
private const int LOGON32_TYPE_NEW_CREDENTIALS = 9;

When using the LOGON32_TYPE_NEW_CREDENTIALS it doesn't throw an error but the impersonated user does not change at all.

I could solve the isse by using the Network Credentials and by using the mpr.dll

[DllImport("mpr.dll")]
private static extern int WNetAddConnection2(NetResource netResource,
     string password, string username, int flags);
[DllImport("mpr.dll")]
     private static extern int WNetCancelConnection2(string name, int flags, bool force);
[StructLayout(LayoutKind.Sequential)]
public class NetResource
{
  public ResourceScope Scope;
  public ResourceType ResourceType;
  public ResourceDisplaytype DisplayType;
  public int Usage;
  public string LocalName;
  public string RemoteName;
  public string Comment;
  public string Provider;
}
public enum ResourceScope : int
{
  Connected = 1,
  GlobalNetwork,
  Remembered,
  Recent,
  Context
};

public enum ResourceType : int
{
  Any = 0,
  Disk = 1,
  Print = 2,
  Reserved = 8,
}

public enum ResourceDisplaytype : int
{
  Generic = 0x0,
  Domain = 0x01,
  Server = 0x02,
  Share = 0x03,
  File = 0x04,
  Group = 0x05,
  Network = 0x06,
  Root = 0x07,
  Shareadmin = 0x08,
  Directory = 0x09,
  Tree = 0x0a,
  Ndscontainer = 0x0b
}

void ConnectToNas(string username, string password, string networkName){
     NetworkCredential cred = new NetworkCredential(username, password);

     var netResource = new NetResource
     {
          Scope = ResourceScope.GlobalNetwork,
          ResourceType = ResourceType.Disk,
          DisplayType = ResourceDisplaytype.Share,
          RemoteName = networkName
     };

     var result = WNetAddConnection2(netResource, credentials.Password,userName,0);

     if (result != 0)
     {
          throw new Win32Exception(result, "Error while connection to NAS");
     }
}

For closing the connection:

void CloseConnection(string networkName){
     WNetCancelConnection2(networkName, 0, true);
}

With this way I was able to connect to the NAS and check if it's readable and writeable by writing a file to it, reading it and afterwards deleting it.