Private Sub cmdstart_Click()
' nächsten freien Laufwerksbuchstaben ermitteln
Dim sDrive As String
sDrive = ""
 
Me.MousePointer = vbHourglass
' Netzlaufwerk verbinden
If AddNetworkDrive(sDrive, Servername,Domänenname und Benutzer, Passwort) = _
  True Then
  lblAnzeige.Caption  = "Laufwerk verbunden Server  xy"
Else
  lblAnzeige.Caption  =  "Zum Server xy konnte nicht verbunden werden"
 
Me.MousePointer = vbDefault
End Sub

Option Explicit
 
' Benötigte API-Deklarationen
Const RESOURCETYPE_DISK = &H1
 
Private Type NETRESOURCE
  dwScope As Long
  dwType As Long
  dwDisplayType As Long
  dwUsage As Long
  lpLocalName As String
  lpRemoteName As String
  lpComment As String
  lpProvider As String
End Type
 
Private Declare Function WNetAddConnection2 Lib "mpr.dll" _
  Alias "WNetAddConnection2A" ( _
  lpNetResource As NETRESOURCE, _
  ByVal lpPassword As String, _
  ByVal lpUserName As String, _
  ByVal dwFlags As Long) As Long
 
' Server verbinden
Public Function AddNetworkDrive(sDriveLetter As String, _
  sNetWorkPath As String, _
  Optional sUserName As String, _
  Optional sPassword As String) As Boolean
 
  Dim nResult As Long
  Dim udtRES As NETRESOURCE
 
  ' NETRESOURCE-Struktur füllen
  With udtRES
    .dwType = RESOURCETYPE_DISK
    .lpLocalName = sDriveLetter
    .lpRemoteName = sNetWorkPath
  End With
 
  ' Netzlaufwerk verbinden
  nResult = WNetAddConnection2(udtRES, sPassword, sUserName, 0)
  If nResult = 0 Then
    AddNetworkDrive = True
  End If
End Function