Изменение прокси в WebBrowser

Private Declare Function UrlMkSetSessionOption Lib "urlmon.dll" _
      (ByVal dwOption As Integer, ByRef pBuffer As INTERNET_PROXY_INFO,
      ByVal dwBufferLength As Integer, ByVal dwReserved As Integer) As Integer

Imports System.Runtime.InteropServices
...
 <Runtime.InteropServices.DllImport("wininet.dll", SetLastError:=True)> _
    Private Shared Function InternetSetOption(ByVal hInternet As IntPtr, ByVal dwOption As Integer, ByVal lpBuffer As IntPtr, ByVal lpdwBufferLength As Integer) As Boolean
    End Function
 
    Public Structure Struct_INTERNET_PROXY_INFO
        Public dwAccessType As Integer
        Public proxy As IntPtr
        Public proxyBypass As IntPtr
    End Structure
 
    Private Sub UseProxy(ByVal strProxy As String)
        Const INTERNET_OPTION_PROXY As Integer = 38
        Const INTERNET_OPEN_TYPE_PROXY As Integer = 3
 
        Dim struct_IPI As Struct_INTERNET_PROXY_INFO
 
        struct_IPI.dwAccessType = INTERNET_OPEN_TYPE_PROXY
        struct_IPI.proxy = Marshal.StringToHGlobalAnsi(strProxy)
        struct_IPI.proxyBypass = Marshal.StringToHGlobalAnsi("local")
 
        Dim intptrStruct As IntPtr = Marshal.AllocCoTaskMem(Marshal.SizeOf(struct_IPI))
 
        Marshal.StructureToPtr(struct_IPI, intptrStruct, True)
 
        Dim iReturn As Boolean = InternetSetOption(IntPtr.Zero, INTERNET_OPTION_PROXY, intptrStruct, System.Runtime.InteropServices.Marshal.SizeOf(struct_IPI))
    End Sub

 UseProxy("ip:port")