Why getting error: System.Net.WebException: Unable to connect to the remote server while upload a file to FTP server using C#?

Question

While uploading the file to Hostinger.com FTP server folder, I'm getting the following error:

System.Net.WebException: 'Unable to connect to the remote server'

Error occurs on this row:

Stream requestStream = request.GetRequestStream();

Please help me! Thanks!

    //FTP Upload
            string sourcefilepath;
            string ftpurl = "ftp://IP/home/u323320256/domains/razidawakhana.com/public_html";
            string ftpusername = "zikria"; // e.g. username
            string ftppassword = "Yamankatita1@"; // e.g. password


            string PureFileName = new FileInfo(file_name).Name;
            String uploadUrl = String.Format("{0}/{1}/{2}", ftpurl, "PDPix", file_name);
            FtpWebRequest request = (FtpWebRequest)WebRequest.Create(uploadUrl);
            request.Method = WebRequestMethods.Ftp.UploadFile;
           

            request.Credentials = new NetworkCredential(ftpusername, ftppassword);
            request.Proxy = null;
            request.KeepAlive = true;
            request.UseBinary = true;
            request.Method = WebRequestMethods.Ftp.UploadFile;

            // Copy the contents of the file to the request stream.  
            StreamReader sourceStream = new StreamReader(_mediaFile.Path);
            byte[] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
            sourceStream.Close();
            request.ContentLength = fileContents.Length;
            Stream requestStream = request.GetRequestStream();
            requestStream.Write(fileContents, 0, fileContents.Length);
            requestStream.Close();
            FtpWebResponse response = (FtpWebResponse)request.GetResponse();
            Console.WriteLine("Upload File Complete, status {0}", response.StatusDescription);
```