Apps Android uploading file not working second time

[purshottam]

I have an andoid application where I am trying to upload a 100KB file on to the server. It uploads in 5 seconds on the server the first time. But next time it either wont upload at all or will take 15 min. to upload
Some time when it does not upload it throws below error that too after 5 min.

03-07 00:02:27.329: E/Debug(27922): error: sendto failed: EPIPE (Broken pipe)


here is my code
Is there any android guru who knows this or all are like me:

Log.d("file_name", ""+existingFileName);
//------------------ CLIENT REQUEST
FileInputStream fileInputStream = new FileInputStream(new File(existingFileName));
// open a URL connection to the Servlet
URL url = new URL(urlString);
// Open a HTTP connection to the URL
conn = (HttpURLConnection) url.openConnection();
// Allow Inputs
conn.setDoInput(true);
// Allow Outputs
conn.setDoOutput(true);
// Don't use a cached copy.
conn.setUseCaches(false);
// Use a post method.
conn.setRequestMethod("POST");
conn.setConnectTimeout(10000); //JP added this for timeout when it crosses the 10 sec bound limit 1 Dec 2014
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
dos = new DataOutputStream(conn.getOutputStream());
dos.writeBytes(twoHyphens + boundary + lineEnd);
dos.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\"" + existingFileName + "\"" + lineEnd);
dos.writeBytes(lineEnd);
// create a buffer of maximum size
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
buffer = new byte[bufferSize];
// read file and write it into form...
bytesRead = fileInputStream.read(buffer, 0, bufferSize);

while (bytesRead > 0) {

dos.write(buffer, 0, bufferSize);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
bytesRead = fileInputStream.read(buffer, 0, bufferSize);

}

// send multipart form data necesssary after file data...
dos.writeBytes(lineEnd);
dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
// close streams
Log.e("Debug", "File is written");
fileInputStream.close();
dos.flush();
dos.close();

} catch (MalformedURLException ex) {
//JP added this on 14 dec 2014
pd.dismiss();
Log.e("Debug", "error: " + ex.getMessage(), ex);
} catch (IOException ioe) {
pd.dismiss();
Log.e("Debug", "error: " + ioe.getMessage(), ioe);
}

//------------------ read the SERVER RESPONSE
try {

inStream = new DataInputStream(conn.getInputStream());
String str;

while ((str = inStream.readLine()) != null) {

Log.e("Debug", "Server Response " + str);

}
inStream.close();
} catch (IOException ioex) {
//JP added this on 14 dec 2014
pd.dismiss();
Log.e("Debug", "error: " + ioex.getMessage(), ioex);
}
return "success";