اتصال به اینترنت

سلام 

من کد زیر رو برای اتصال به اینترنت قرار میدم منتها بعضی  وقت ها که اتصال به اینترنت مشکل نداره و وصل هست پیعام coneection error  رو میده

 private String errorMessage;

 private void check_Network() {
       new NetCheck().execute();
 }

 private class NetCheck extends AsyncTask<String, String, Boolean> {

        @Override
        protected Boolean doInBackground(String... args) {

            ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = cm.getActiveNetworkInfo();

            if (networkInfo == null) {
                errorMessage = "Connect to a Network";
                return false;
            }

            if (networkInfo.isConnected()) {

                try {
                    URL url = new URL("http://www.google.com");
                    HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
                    urlc.setConnectTimeout(3000);
                    urlc.connect();

                    errorMessage = urlc.getResponseCode() == 200 ? "Successful Connection": "Internet Error";
                    return urlc.getResponseCode() == 200;
                }
                catch (SocketTimeoutException e) {
                    errorMessage = "Connection Error";
                    return false;
                }
                catch (MalformedURLException e) {
                    errorMessage = "Connection Error";
                    return false;
                }
                catch (IOException e) {
                    errorMessage = "Connection Error";
                    return false;
                }
            }

            errorMessage = "Network Disabled";
            return false;
        }

        //-------------------------------------------------
        @Override
        protected void onPostExecute(Boolean isConnected) {

            if ( !isConnected) { // code if not connected

            AlertDialog.Builder builder = new AlertDialog.Builder(G.activity);
            builder.setMessage(errorMessage);
            builder.setCancelable(false);

            builder.setPositiveButton("Try Again", new DialogInterface.OnClickListener() {

                @Override
                public void onClick(DialogInterface dialog, int id) {
                    dialog.cancel();
 check_Network();
                }
            });

            AlertDialog alertDialog = builder.create();
            alertDialog.show();
        } else { // code if connected
            Toast.makeText(G.context, errorMessage, 3000).show();
        }
        }
 }