// receiver
    auto receiver = new QUdpSocket(&app);
    if (!receiver->bind()) {
        qFatal("bind() failed");
    }
    auto localPort = receiver->localPort();
    QObject::connect(receiver,&QUdpSocket::readyRead, receiver, [receiver]() {
        QByteArray data(receiver->pendingDatagramSize(), Qt::Uninitialized);
        receiver->readDatagram(data.data(), data.size());
    });

    // sender
    auto sender = new QUdpSocket(&app);
    auto timer = new QTimer(&app);
    timer->setInterval(0);
    timer->setSingleShot(false);
    QObject::connect(timer, &QTimer::timeout, sender, [sender,localPort]() {
        sender->writeDatagram({},QHostAddress::LocalHost, localPort);
    });
    timer->start();