Here is the wiring diagram for this circuit. The diagram shows it being wired using an Arduino Pro Micro board, which has a built-in USB programming port. The rest of the pictures here show building the same circuit but using a Pro Mini board instead. Either will work fine. Any diode will work, but a 1N5817 is the best kind to use. The Buck converter at top left should output 5.0V. The ethernet module used is a W5500 type, with an onboard 3.3V regulator.