Qt UDP network accessing to camera connected by LAN

Hello, I am trying to get data from a LAN-connected infrared camera.
I don't know how to receive packets from the external network.
Here's my code.

Code:

MyUDP::MyUDP(QObject *parent) :
    QObject(parent)
{
    // create a QUDP socket
    socket = new QUdpSocket(this);
    socket_cam = new QUdpSocket(this);
    // The most common way to use QUdpSocket class is
    // to bind to an address and port using bind()
    // bool QAbstractSocket::bind(const QHostAddress & address,
    //     quint16 port = 0, BindMode mode = DefaultForPlatform)
    socket->bind(QHostAddress::LocalHost, 1234);
 
    connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()));
}
 
void MyUDP::HelloUDP()
{
    QByteArray Data;
 
    QHostAddress camera_loc = QHostAddress("192.168.10.197");
    quint16 cameraPort = 32197;
 
    qint64 deg_num = socket->readDatagram(Data.data() ,964, &camera_loc, &cameraPort);
    qDebug() << "Deg_num: " << deg_num; //this returns -1. Therefore, it seems it can't read any data from camera_loc.
    // Sends the datagram datagram
    // to the host address and at port.
    // qint64 QUdpSocket::writeDatagram(const QByteArray & datagram,
    //                      const QHostAddress & host, quint16 port)
    socket->writeDatagram(Data, QHostAddress::LocalHost, 1234);
}
 
void MyUDP::readyRead()
{
    // when data comes in
    QByteArray buffer;
    buffer.resize(socket->pendingDatagramSize());
 
    QHostAddress sender = QHostAddress("192.168.10.197");
    quint16 senderPort = 32197;
 
    // qint64 QUdpSocket::readDatagram(char * data, qint64 maxSize,
    //                 QHostAddress * address = 0, quint16 * port = 0)
    // Receives a datagram no larger than maxSize bytes and stores it in data.
    // The sender's host address and port is stored in *address and *port
    // (unless the pointers are 0).
 
    socket->readDatagram(buffer.data(), buffer.size(),
                         &sender, &senderPort);
    qDebug() << "Message from: " << sender.toString();
    qDebug() << "Message port: " << senderPort;
    qDebug() << "Message: " << buffer;
}

I changed a little from Qt5 Tutorial QUdpSocket(https://www.bogotobogo.com/Qt/Qt5_QUdpSocket.php)
As I've seen on Wireshark, packets arrived correctly as I expected.
However, my code doesn't work as I expected. (readDatagram on camera_loc returns (-1))
According to other threads, we don't need to connect them because UDP communication doesn't need to make connections.
What I want to make with this code is as follow.

(0. Save data from the camera (192.168.10.197) on a variable using readDatagram) I am not sure this is a really necessary process...:o
1. Write data to buffer as written in this code (using writeDatagram function).

I could not find solutions even if I struggled. :)
I thought it would be easy but it wasn't ...
Any advice will be very grateful because I am a newbie to qt and UDP network.

Thanks in advance. ;)

RadioKong