QMQTT does not connect signal

Description:

When MQTT over QSslSocket by QMqttConnection::setTransport(ssocket, QMqttClient::SecureSocket), then signal QAbstractSocket::connected and QAbstractSocket::disconnected is lost.

The following is my code. FYI. thanks.

void QMqttConnection::setTransport(QIODevice *device, QMqttClient::TransportType transport)
{
qCDebug(lcMqttConnection) << Q_FUNC_INFO << device << " Type:" << transport;

if (m_transport) {
disconnect(m_transport, &QIODevice::aboutToClose, this, &QMqttConnection::transportConnectionClosed);
disconnect(m_transport, &QIODevice::readyRead, this, &QMqttConnection::transportReadReady);

// Start: Added By Jerry.Liu (jerry-liu@outlook.com)
auto socket = dynamic_cast<QAbstractSocket*>(m_transport);
if (socket) {
disconnect(socket, &QAbstractSocket::connected, this, &QMqttConnection::transportConnectionEstablished);
disconnect(socket, &QAbstractSocket::disconnected, this, &QMqttConnection::transportConnectionClosed);
}
// End: Added By Jerry (jerry-liu@outlook.com)
if (m_ownTransport)
delete m_transport;
}

m_transport = device;
m_transportType = transport;
m_ownTransport = false;

connect(m_transport, &QIODevice::aboutToClose, this, &QMqttConnection::transportConnectionClosed);
connect(m_transport, &QIODevice::readyRead, this, &QMqttConnection::transportReadReady);

// Start: Added By Jerry.Liu (jerry-liu@outlook.com)
auto socket = dynamic_cast<QAbstractSocket*>(device);
if (socket){
bool ret = false;
ret = connect(socket, &QAbstractSocket::connected, this, &QMqttConnection::transportConnectionEstablished);
Q_ASSERT(ret);
ret = connect(socket, &QAbstractSocket::disconnected, this, &QMqttConnection::transportConnectionClosed);
Q_ASSERT(ret);
}
// End: Added By Jerry (jerry-liu@outlook.com)
}