This handy little PCB that Howard Dutton designed allows you to put a hard wired ethernet connector in the same foot print as the ESP8266 commonly used for WiFi with OnStep.
You need to supply a Teensy 4.0 MCU and a W5500 ethernet module.
I keep a limited supply of Teensy MCUs on hand. So check with me if inventory shows zero.
You can also purchse the Teensy MCUs at this URL. https://www.pjrc.com/store/teensy40.html