mutiple requests not work

[jplajpla23]

Im design an app that send a UDP broadcast.
my code is simple send a fixed packet when i click in button. this is the function that is called. nut the problem is that the frist time work, the second show sent X bytes but not receive anything in others devices or response. i check with wireshart and the packet is not sent. sometimes can send 2/3 times but some only the first

searchDevices() async {

var sender = await UDP.bind(Endpoint.any(port: Port.any));
devices=[];

sender.socket?.broadcastEnabled=true;
// send a simple string to a broadcast endpoint on port 65001.

//sender.as

// creates a new UDP instance and binds it to the local address and the port
// 65002.
//var receiver = await UDP.bind(Endpoint.any(port: Port.any));
//receiver.socket?.broadcastEnabled=true;
// receiving\listening
sender.asStream(timeout: Duration(seconds: 5)).listen((datagram) {
  var str = String.fromCharCodes(datagram!.data);
  print(str);
  devices.add(str);

  ScaffoldMessenger.of(context).showSnackBar(
    SnackBar(content: Text(str)),
  );

  // receiver.close();
});


var dataLength = await sender.send( numbers, Endpoint.broadcast(port: Port(9998)));

print('$dataLength bytes sent.');
//receiver.socket.broadcastEnabled


// close the UDP instances and their sockets.
await Future.delayed(Duration(seconds: 5)); // Wait for responses.

// sender.close();

}