Issue with UDP message reception in QT - c++

Question

I want to receive UDP messages using QT. The code I use (see bellow) works well, but the problem is that it only works for one message: after receiving one message, the code still running, but it seems that it doesn't receive anything anymore.
Indeed, after the first message received, the console display qDebug() << "in !";, meaning that it enters into the function, but never received other UDP messages.
I already check, I sure the message is well sent by the UDP server. So the problem must come from here. Any suggestions?
Launching UDP when the class is created:
App::App(QWidget *parent)
: QMainWindow(parent), imageLabel(new QLabel)
, scrollArea(new QScrollArea)
{
.....
StartUDP();
....
}
The UDP initialization:
void App::StartUDP()
{
socket = new QUdpSocket(this);
bool result = socket->bind(QHostAddress::AnyIPv4, 17);
qDebug() << result;
if(result)
{
qDebug() << "PASS";
}
else
{
qDebug() << "FAIL";
}
readyRead();
connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()),Qt::QueuedConnection);
}
The function that what for UDP signal:
void App::readyRead()
{
qDebug() << "in !";
QHostAddress sender;
quint16 port;
while (socket->hasPendingDatagrams())
{
QByteArray datagram;
datagram.resize(socket->pendingDatagramSize());
socket->readDatagram(datagram.data(),datagram.size(),&sender,&port);
qDebug() <<"Message From :: " << sender.toString();
qDebug() <<"Port From :: "<< port;
qDebug() <<"Message :: " << datagram;
file_name = datagram;
m_SystemTrayIcon->showMessage(tr("Message"), tr("Nouveau fichier détecté"));
}
}