I've built an ethernet gateway with a genuine Arduino Uno and an ENC28J60 ethernet module. I was getting a check wires error until I started powering the ENC28J60 with a seperate power supply. Now I am getting the Gateway Startup Complete message, which is great, but when I try to ping my device it is not on my network.
Here is my sketch if that is helpful:
/**
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 *******************************
 *
 * REVISION HISTORY
 * Version 1.0 - Henrik EKblad
 * Contribution by a-lurker and Anticimex, 
 * Contribution by Norbert Truchsess <norbert.truchsess@t-online.de>
 *
 * 
 * DESCRIPTION
 * The EthernetGateway sends data received from sensors to the ethernet link. 
 * The gateway also accepts input on ethernet interface, which is then sent out to the radio network.
 *
 * The GW code is designed for Arduino 328p / 16MHz.  ATmega168 does not have enough memory to run this program.
 * 
 *
 * COMPILING WIZNET (W5100) ETHERNET MODULE
 * > Edit MyConfig.h in (libraries\MySensors\) to enable softspi (remove // before "#define SOFTSPI").
 *
 * COMPILING ENC28J60 ETHERNET MODULE
 * > Use Arduino IDE 1.5.7 (or later) 
 * > Disable DEBUG in Sensor.h before compiling this sketch. Othervise the sketch will probably not fit in program space when downloading. 
 * > Remove Ethernet.h include below and include UIPEthernet.h 
 * > Remove DigitalIO include 
 * Note that I had to disable UDP and DHCP support in uipethernet-conf.h to reduce space. (which means you have to choose a static IP for that module)
 *
 * VERA CONFIGURATION:
 * Enter "ip-number:port" in the ip-field of the Arduino GW device. This will temporarily override any serial configuration for the Vera plugin. 
 * E.g. If you want to use the defualt values in this sketch enter: 192.168.178.66:5003
 *
 * LED purposes:
 * - To use the feature, uncomment WITH_LEDS_BLINKING in MyConfig.h
 * - RX (green) - blink fast on radio message recieved. In inclusion mode will blink fast only on presentation recieved
 * - TX (yellow) - blink fast on radio message transmitted. In inclusion mode will blink slowly
 * - ERR (red) - fast blink on error during transmission error or recieve crc error  
 * 
 * See http://www.mysensors.org/build/ethernet_gateway for wiring instructions.
 *
 */
#define NO_PORTB_PINCHANGES 
//#include <DigitalIO.h>     // This include can be removed when using UIPEthernet module  
#include <SPI.h>  
#include <MySigningNone.h>
#include <MyTransportRFM69.h>
#include <MyTransportNRF24.h>
#include <MyHwATMega328.h>
#include <MySigningAtsha204Soft.h>
#include <MySigningAtsha204.h>
#include <MyParserSerial.h>  
#include <MySensor.h>  
#include <stdarg.h>
#include <PinChangeInt.h>
#include "GatewayUtil.h"
// Use this if you have attached a Ethernet ENC28J60 shields  
 #include <UIPEthernet.h>  
// Use this for WizNET W5100 module and Arduino Ethernet Shield 
//#include <Ethernet.h>   
#define INCLUSION_MODE_TIME 1 // Number of minutes inclusion mode is enabled
#define INCLUSION_MODE_PIN  3 // Digital pin used for inclusion mode button
#define RADIO_CE_PIN        5  // radio chip enable
#define RADIO_SPI_SS_PIN    6  // radio SPI serial select
#define RADIO_ERROR_LED_PIN 7  // Error led pin
#define RADIO_RX_LED_PIN    8  // Receive led pin
#define RADIO_TX_LED_PIN    9  // the PCB, on board LED
// NRFRF24L01 radio driver (set low transmit power by default) 
MyTransportNRF24 transport(RADIO_CE_PIN, RADIO_SPI_SS_PIN, RF24_PA_LEVEL_GW);  
//MyTransportRFM69 transport;
// Message signing driver (signer needed if MY_SIGNING_FEATURE is turned on in MyConfig.h)
//MySigningNone signer;
//MySigningAtsha204Soft signer;
//MySigningAtsha204 signer;
// Hardware profile 
MyHwATMega328 hw;
// Construct MySensors library (signer needed if MY_SIGNING_FEATURE is turned on in MyConfig.h)
// To use LEDs blinking, uncomment WITH_LEDS_BLINKING in MyConfig.h
#ifdef WITH_LEDS_BLINKING
MySensor gw(transport, hw /*, signer*/, RADIO_RX_LED_PIN, RADIO_TX_LED_PIN, RADIO_ERROR_LED_PIN);
#else
MySensor gw(transport, hw /*, signer*/);
#endif
#define IP_PORT 5003        // The port you want to open 
IPAddress myIp (192, 168, 1, 25);  // Configure your static ip-address here    COMPILE ERROR HERE? Use Arduino IDE 1.5.7 or later!
// The MAC address can be anything you want but should be unique on your network.
// Newer boards have a MAC address printed on the underside of the PCB, which you can (optionally) use.
// Note that most of the Ardunio examples use  "DEAD BEEF FEED" for the MAC address.
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };  // DEAD BEEF FEED
// a R/W server on the port
EthernetServer server = EthernetServer(IP_PORT);
// handle to open connection
EthernetClient client = EthernetClient();
char inputString[MAX_RECEIVE_LENGTH] = "";    // A string to hold incoming commands from serial/ethernet interface
int inputPos = 0;
bool sentReady = false;
void output(const char *fmt, ... ) {
   va_list args;
   va_start (args, fmt );
   vsnprintf_P(serialBuffer, MAX_SEND_LENGTH, fmt, args);
   va_end (args);
   Serial.print(serialBuffer);
   server.write(serialBuffer);
}
void setup()  
{ 
  Ethernet.begin(mac, myIp);
  setupGateway(INCLUSION_MODE_PIN, INCLUSION_MODE_TIME, output);
  // Add interrupt for inclusion button to pin
  PCintPort::attachInterrupt(pinInclusion, startInclusionInterrupt, RISING);
  // give the Ethernet interface a second to initialize
  delay(1000);
  // Initialize gateway at maximum PA level, channel 70 and callback for write operations 
  gw.begin(incomingMessage, 0, true, 0);
  
  // start listening for clients
  server.begin();
}
void loop() {
  gw.process();  
  
  checkButtonTriggeredInclusion();
  checkInclusionFinished();
  
  // if an incoming client connects, there will be
  // bytes available to read via the client object
  EthernetClient newclient = server.available();
  // if a new client connects make sure to dispose any previous existing sockets
  if (newclient) {
      if (client != newclient) {
       client.stop();
       client = newclient;
       output(PSTR("0;0;%d;0;%d;Gateway startup complete.\n"),  C_INTERNAL, I_GATEWAY_READY);
     }
   }
         
   if (client) {
     if (!client.connected()) {
       client.stop();
     } else if (client.available()) { 
       // read the bytes incoming from the client
       char inChar = client.read();
       if (inputPos<MAX_RECEIVE_LENGTH-1) { 
         // if newline then command is complete
         if (inChar == '\n') {  
           Serial.println("Finished");
            // a command was issued by the client
            // we will now try to send it to the actuator
            inputString[inputPos] = 0;
      
            // echo the string to the serial port
            Serial.print(inputString);
      
            parseAndSend(gw, inputString);
      
            // clear the string:
            inputPos = 0;
         } else {  
           // add it to the inputString:
           inputString[inputPos] = inChar;
           inputPos++;
         }
      } else {
         // Incoming message too long. Throw away 
         inputPos = 0;
      }
    }
  }
}