Arduino - Compiling Sample sketch file

Which microcontroller? What is the code? What are the error messages? You should open an issue on the CNMAT GitHub site. I'm the maintainer of the TCP extension and the code was tested with a WIZNet EVB-5500 Pico board (have a look to the EOS example of the library).

Hi,

This is with an Arduino Uno R3, connected via USB

However, I have managed to sort, thanks for your reply. It was a mistake I had made, still learning!