(ask) Port unreachable

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Java

UDP

sockets

WiFi

ports

hello everyone, I'd like to ask why is this error occurs.
I am trying to get a string data from a device. I have make this code and it runs well when I try to obtain data from a local server, but it stated this error when it connects to the device.

java.net.PortUnreachableException: ICMP Port Unreachable
	at java.net.DualStackPlainDatagramSocketImpl.socketReceiveOrPeekData(Native Method)
	at java.net.DualStackPlainDatagramSocketImpl.receive0(DualStackPlainDatagramSocketImpl.java:105)
	at java.net.AbstractPlainDatagramSocketImpl.receive(AbstractPlainDatagramSocketImpl.java:145)
	at java.net.DatagramSocket.receive(DatagramSocket.java:786)
	at udp_test.main(udp_test.java:28)

here is my code

public class udp_test
{
	public static void main(String[] args) throws IOException
	{
		InetAddress IP = InetAddress.getByName("192.168.1.2");
		int port = 5551;
		
		while (true)
		{
			try
			{
				byte [] datapacket = new byte [4];
				
				DatagramSocket ds = new DatagramSocket();
				DatagramPacket dp = new DatagramPacket(datapacket, datapacket.length);
			
				ds.setSoTimeout(100);
				ds.connect(IP, port);
				ds.send(dp);
				ds.isConnected();
			
				ds.receive(dp);
				ds.close();
			
				String strRecv = new String(dp.getData(), 0, dp.getLength()) + " from "
						+ dp.getAddress().getHostAddress() + " port " + dp.getPort();
			
				System.out.println(strRecv);
				
				try {
					Thread.sleep(1000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			catch (SocketException e)
			{
			// TODO Auto-generated catch block
			e.printStackTrace();
			}	
		}	
	}
}

it's simply change the IP address, byte size and port when I connect to my device or should I change something else?

thanks before