Bug in QSerialPort

Hello
I have several problems for QSerialPort in Windows 10 and version qt 6.6.0
First, I have a question about using QSerialPort.
In Windows I understand that for the communication between the program and the device to work I have to set "serialport" as open and then:
_serial_port->setDataTerminalReady(true);
But it is ALWAYS FALSE and never changes anywhere in the program but it is mandatory for the program.(I also tried to remove it)

I don't know if you have modified this over time or if it is a bug or if it is the cause of:
When I request data from the device, at "random" times, the device crashes and returns nothing.
And I have checked with other "realterm" type programs and it works perfect so the device is fine.
But in QT, it fails.
Example using QT + Telnet:

As you can see, for example, it fails and it doesnt return "64" when i say "gf" in random moments,so readyread is not emitted since "it isn't available data".. When i say "it isn't available data", it means that bytesavailable() return 0 before readyread signal.
So i want to know if it its a bug from QT in windows or whatever...

Code of the config:

I hope that it can be fixed as soon as possible or at least...that we can confirm that it is a bug or not.

Best regards