要引用一下System.management.dll

Dim query As System.Management.ManagementObjectSearcher = New System.Management.ManagementObjectSearcher("SELECT * FROM Win32_NetworkAdapterConfiguration")
Dim queryCollection As System.Management.ManagementObjectCollection = query.Get()
Dim mo As New System.Management.ManagementObject
For Each mo In queryCollection
    If Convert.ToBoolean(mo("ipEnabled")) = True
        If mo("DefaultIPGateway") IsNot Nothing Then          
            MessageBox.Show( mo("DefaultIPGateway")(0))
        End If
    End If
Next