have a read of how-to-get-the-best-out-of-this-forum
in particular:
what host microcontroller are you using? e.g. UNO, Mega, ESP32, RP2040???
what ethernet board are you using? give a link or a photo?
how have you connected the Ethernet module to the host?
did you test the Ethernet module in a separate program before connected any other devices?