Hello Felix, Thank you for your feedback.

I am new to the subject, but I still tried to modify the Wifi library but nothing to do. I do not see how to do with the Ethenet.
really if someone has a solution I am interested in doing tests

 I'd like to know if anyone's ever programmed the M5Stack core basic + PoE LAN module as a modbus tcp ethernet slave on arduino.
If so, which library did you use? Could I get a sample code?
I'm new to arduino programming and I'm just discovering the M5Stack.
thanks for your feedback