Set proxy for windows forms application web browser

I've implemented proxy for my windows forms application. It was working fine but somehow it stopped working on some machines. I think some windows updates triggered this but I could not find the issue because I'm unable to reproduce it in my computer. Did something change in some of the windows updates? You can check my code below. In RestoreSystemProxy() method bReturn is false and it cannot do any proxy changes. `using System; using System.Runtime.InteropServices;

namespace Insurance { public static class WinInetInterop { public static string ApplicationName;

    [DllImport("wininet.dll", SetLastError = true, CharSet = CharSet.Auto)]
    private static extern IntPtr InternetOpen(
        string lpszAgent, int dwAccessType, string lpszProxyName,
        string lpszProxyBypass, int dwFlags);

    [DllImport("wininet.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool InternetCloseHandle(IntPtr hInternet);

    public struct StructInternetProxyInfo
    {
        public int DwAccessType;
        public IntPtr Proxy;
        public IntPtr ProxyBypass;
    };

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
    private struct INTERNET_PER_CONN_OPTION_LIST
    {
        public int Size;

        // The connection to be set. NULL means LAN.
        public System.IntPtr Connection;

        public int OptionCount;
        public int OptionError;

        // List of INTERNET_PER_CONN_OPTIONs.
        public System.IntPtr pOptions;
    }
    private enum INTERNET_OPTION
    {
        // Sets or retrieves an INTERNET_PER_CONN_OPTION_LIST structure that specifies
        // a list of options for a particular connection.
        INTERNET_OPTION_PER_CONNECTION_OPTION = 75,

        // Notify the system that the registry settings have been changed so that
        // it verifies the settings on the next call to InternetConnect.
        INTERNET_OPTION_SETTINGS_CHANGED = 39,

        // Causes the proxy data to be reread from the registry for a handle.
        INTERNET_OPTION_REFRESH = 37

    }

    private enum INTERNET_PER_CONN_OptionEnum
    {
        INTERNET_PER_CONN_FLAGS = 1,
        INTERNET_PER_CONN_PROXY_SERVER = 2,
        INTERNET_PER_CONN_PROXY_BYPASS = 3,
        INTERNET_PER_CONN_AUTOCONFIG_URL = 4,
        INTERNET_PER_CONN_AUTODISCOVERY_FLAGS = 5,
        INTERNET_PER_CONN_AUTOCONFIG_SECONDARY_URL = 6,
        INTERNET_PER_CONN_AUTOCONFIG_RELOAD_DELAY_MINS = 7,
        INTERNET_PER_CONN_AUTOCONFIG_LAST_DETECT_TIME = 8,
        INTERNET_PER_CONN_AUTOCONFIG_LAST_DETECT_URL = 9,
        INTERNET_PER_CONN_FLAGS_UI = 10
    }

    [DllImport("wininet.dll", CharSet = CharSet.Ansi, SetLastError = true,
           EntryPoint = "InternetQueryOption")]
    private extern static bool InternetQueryOptionList(
        IntPtr Handle,
        INTERNET_OPTION OptionFlag,
        ref INTERNET_PER_CONN_OPTION_LIST OptionList,
        ref int size);

    /// <summary>
    /// Backup the current options for LAN connection.
    /// Make sure free the memory after restoration. 
    /// </summary>
    private static INTERNET_PER_CONN_OPTION_LIST GetSystemProxy()
    {

        // Query following options. 
        INTERNET_PER_CONN_OPTION[] Options = new INTERNET_PER_CONN_OPTION[3];

        Options[0] = new INTERNET_PER_CONN_OPTION();
        Options[0].dwOption = (int)INTERNET_PER_CONN_OptionEnum.INTERNET_PER_CONN_FLAGS;
        Options[1] = new INTERNET_PER_CONN_OPTION();
        Options[1].dwOption = (int)INTERNET_PER_CONN_OptionEnum.INTERNET_PER_CONN_PROXY_SERVER;
        Options[2] = new INTERNET_PER_CONN_OPTION();
        Options[2].dwOption = (int)INTERNET_PER_CONN_OptionEnum.INTERNET_PER_CONN_PROXY_BYPASS;

        // Allocate a block of memory of the options.
        System.IntPtr buffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(Options[0])
            + Marshal.SizeOf(Options[1]) + Marshal.SizeOf(Options[2]));

        System.IntPtr current = (System.IntPtr)buffer;

        // Marshal data from a managed object to an unmanaged block of memory.
        for (int i = 0; i < Options.Length; i++)
        {
            Marshal.StructureToPtr(Options[i], current, false);
            current = (System.IntPtr)((int)current + Marshal.SizeOf(Options[i]));
        }

        // Initialize a INTERNET_PER_CONN_OPTION_LIST instance.
        INTERNET_PER_CONN_OPTION_LIST Request = new INTERNET_PER_CONN_OPTION_LIST();

        // Point to the allocated memory.
        Request.pOptions = buffer;

        Request.Size = Marshal.SizeOf(Request);

        // IntPtr.Zero means LAN connection.
        Request.Connection = IntPtr.Zero;

        Request.OptionCount = Options.Length;
        Request.OptionError = 0;
        int size = Marshal.SizeOf(Request);

        // Query internet options. 
        bool result = InternetQueryOptionList(IntPtr.Zero,
            INTERNET_OPTION.INTERNET_OPTION_PER_CONNECTION_OPTION,
            ref Request, ref size);
        if (!result)
        {
            throw new ApplicationException(" Set Internet Option Failed! ");
        }

        return Request;
    }

    private const int INTERNET_OPEN_TYPE_DIRECT = 1;  // direct to net
    private const int INTERNET_OPEN_TYPE_PRECONFIG = 0; // read registry
    /// <summary>
    /// Constants used in INTERNET_PER_CONN_OPTON struct.
    /// </summary>
    private enum INTERNET_OPTION_PER_CONN_FLAGS
    {
        PROXY_TYPE_DIRECT = 0x00000001,   // direct to net
        PROXY_TYPE_PROXY = 0x00000002,   // via named proxy
        PROXY_TYPE_AUTO_PROXY_URL = 0x00000004,   // autoproxy URL
        PROXY_TYPE_AUTO_DETECT = 0x00000008   // use autoproxy detection
    }

    /// <summary>
    /// Used in INTERNET_PER_CONN_OPTION.
    /// When create a instance of OptionUnion, only one filed will be used.
    /// The StructLayout and FieldOffset attributes could help to decrease the struct size.
    /// </summary>
    [StructLayout(LayoutKind.Explicit)]
    private struct INTERNET_PER_CONN_OPTION_OptionUnion
    {
        // A value in INTERNET_OPTION_PER_CONN_FLAGS.
        [FieldOffset(0)]
        public int dwValue;
        [FieldOffset(0)]
        public System.IntPtr pszValue;
        [FieldOffset(0)]
        public System.Runtime.InteropServices.ComTypes.FILETIME ftValue;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct INTERNET_PER_CONN_OPTION
    {
        // A value in INTERNET_PER_CONN_OptionEnum.
        public int dwOption;
        public INTERNET_PER_CONN_OPTION_OptionUnion Value;
    }
    /// <summary>
    /// Sets an Internet option.
    /// </summary>
    [DllImport("wininet.dll", CharSet = CharSet.Ansi, SetLastError = true)]
    private static extern bool InternetSetOption(
        IntPtr hInternet,
        INTERNET_OPTION dwOption,
        IntPtr lpBuffer,
        int lpdwBufferLength);

    [DllImport("wininet.dll", SetLastError = true)]
    private static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int lpdwBufferLength);

    public static void RefreshIESettings(string strProxy)
    {
        const int internetOptionProxy = 38;
        const int internetOpenTypeProxy = 3;

        StructInternetProxyInfo structIpi;

        // Filling in structure 
        structIpi.DwAccessType = internetOpenTypeProxy;
        structIpi.Proxy = Marshal.StringToHGlobalAnsi(strProxy);
        structIpi.ProxyBypass = Marshal.StringToHGlobalAnsi("local");

        // Allocating memory 
        IntPtr intptrStruct = Marshal.AllocCoTaskMem(Marshal.SizeOf(structIpi));

        // Converting structure to IntPtr 
        Marshal.StructureToPtr(structIpi, intptrStruct, true);

        var iReturn = InternetSetOption(IntPtr.Zero, internetOptionProxy, intptrStruct, Marshal.SizeOf(structIpi));
    }

    /// <summary>
    /// Restore the options for LAN connection.
    /// </summary>
    /// <returns></returns>
    public static bool RestoreSystemProxy()
    {
        IntPtr hInternet = InternetOpen(ApplicationName, INTERNET_OPEN_TYPE_DIRECT, null, null, 0);

        INTERNET_PER_CONN_OPTION_LIST request = GetSystemProxy();
        int size = Marshal.SizeOf(request);

        // Allocate memory. 
        IntPtr intptrStruct = Marshal.AllocCoTaskMem(size);

        // Convert structure to IntPtr 
        Marshal.StructureToPtr(request, intptrStruct, true);

        // Set internet options.
        bool bReturn = InternetSetOption(hInternet,
            INTERNET_OPTION.INTERNET_OPTION_PER_CONNECTION_OPTION,
            intptrStruct, size);

        // Free the allocated memory.
        Marshal.FreeCoTaskMem(request.pOptions);
        Marshal.FreeCoTaskMem(intptrStruct);

        if (!bReturn)
        {
            throw new Exception(" Set Internet Option Failed! ");
        }

        // Notify the system that the registry settings have been changed and cause
        // the proxy data to be reread from the registry for a handle.
        InternetSetOption(hInternet, INTERNET_OPTION.INTERNET_OPTION_SETTINGS_CHANGED,
            IntPtr.Zero, 0);
        InternetSetOption(hInternet, INTERNET_OPTION.INTERNET_OPTION_REFRESH,
            IntPtr.Zero, 0);

        InternetCloseHandle(hInternet);

        return bReturn;
    }

}

} `