PL62-W as a server TCP/IP | Telit Cinterion IoT Developer Community

I'm developing a server with the PLS62-W module, but I'm having difficulties connecting to this device.
I'm using a variable IP, so whenever the firmware runs the IP will be modified.
When I try to connect to any IP provided by the APN, nothing happens (the server remains waiting for the client to connect). My question is, is there any other parameter that I am failing to configure?
​
Here is the developed firmware:

package threads;

import java.io.*;
import java.util.*;
import javax.microedition.io.*;
import sockets.SocketRoteamento2;

public class ThreadSocketListener extends Thread {

	public static boolean loopTimers = true;

	private static ThreadSocketListener instance = null;

	// StreamConnectionNotifier serverConnection;

	//int port = 47002;

	DataInputStream is;
	DataInputStream os;
	ServerSocketConnection serverConnection;
	SocketConnection socketconnection;
	
	
	// Field descriptor #5 B
	public static final byte DELAY = 0;

	// Field descriptor #5 B
	public static final byte LINGER = 1;

	// Field descriptor #5 B
	public static final byte KEEPALIVE = 2;

	// Field descriptor #5 B
	public static final byte RCVBUF = 3;

	// Field descriptor #5 B
	public static final byte SNDBUF = 4;

	public ThreadSocketListener getInstance() {

		if (instance == null) {
			instance = new ThreadSocketListener();
			instance.init();
		}
		return instance;
	}

	private void init() {

	}

	public void run() {

		try {

			ServerSocketConnection serverConnection = (ServerSocketConnection) Connector.open("socket://" + ":50018");


			while (true) {

				System.out.println("Waiting for connection on port: 50018");

				SocketConnection socketconnection = (SocketConnection) serverConnection.acceptAndOpen();

				System.out.println("Connection to established.");

				try {
					Thread.sleep(1000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}

				// Get the input stream of the connection.
				DataInputStream is = socketconnection.openDataInputStream();

				// Get the output stream of the connection.
				DataOutputStream os = socketconnection.openDataOutputStream();

				// Read the input data.
				// String result = is.readUTF();

				String resultado = is.readUTF();

				System.out.println(resultado);

				String result = "Helloword";

				// Echo the data back to the sender.
				os.write(result.getBytes());

				serverConnection.close();

				socketconnection.close();

				is.close();

				os.close();
			}

		} catch (IOException e) {
			System.out.println(e.toString() + " Exception");

			try {
				serverConnection.close();
				socketconnection.close();
			} catch (IOException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}

		}

	}
}

Best regards,
Pedro.