How do I pull all 100 pages from 3rd party API using webrequest

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C#5.0

I created one C# web service where
1. First i finds no of pages for that date range
2. After that in Loop I made Page request after 3rd request i Got 524 Error

private string postPaymentRequestToGateway(String queryUrl, String urlParam)
{

String message = "";
StreamWriter myWriter = null;// it will open a http connection with provided url
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
WebRequest objRequest = WebRequest.Create(queryUrl);//send data using objxmlhttp object
WriteToFile("Request Time Before Response " + System.DateTime.Now);
objRequest.Method = "POST";
try
{
objRequest.ContentType = "application/x-www-form-urlencoded";//to set content type
myWriter = new System.IO.StreamWriter(objRequest.GetRequestStream());
myWriter.Write(urlParam);//send data
myWriter.Close();//closed the myWriter objec=-[ TR

// Getting Response
//using (System.Net.HttpWebResponse objResponse = (System.Net.HttpWebResponse)objRequest.GetResponse())
using (WebResponse objResponse = objRequest.GetResponse())
//receive the responce from objxmlhttp object
{
//Thread.Sleep(10000);
WriteToFile("Request Time After Response " + System.DateTime.Now);
using (System.IO.StreamReader sr = new System.IO.StreamReader(objResponse.GetResponseStream()))
{
message = sr.ReadToEnd();
sr.Close();
}
//WriteToFile("Request Time After Response Message " + message);
}

}

catch (Exception exception)
{

WriteToFile("Inner Exception Stack" + exception.StackTrace);
WriteToFile("Inner Exception " + exception.InnerException.Message);
}
finally
{
objRequest.Abort();

myWriter.Close();//closed the myWriter object//05April2019

}
return message;

}

What I have tried:

For this I added objRequest.Abort(); in finally method
I tried various options but I Cant find solution .
Error in objRequest.GetResponse()) where Response takes more time after third pages
and then timeout error .
Can anyone tell me how to resolve this problem?.......