Ethernet Shield Troubles

Hey all,
I have had an Arduino for over a year and a bit now but I’m pretty new to the Ethernet scene. I recently bought a Duinotech Arduino Ethernet Shield to go with my Freetronics Eleven but have encountered some problems in accessing the ip address used for the tutorial DCHP AdressPrinter. My board did not come with a labelled mac address nor did it come with any sort of sticker with the mac address on it. So being kind of new I picked up that it would be alright to create your own for the board as long as it didn’t interfere with any other devices, so I went ahead got the program working working once on a specific mac and ip address and then transferred the Mac and ip address into a different example with it rendering the connection useless. I have absolutely not a clue what to do.

Here is my code:

DHCP-based IP printer

This sketch uses the DHCP extensions to the Ethernet library
to get an IP address via DHCP and print the address obtained.
using an Arduino Wiznet Ethernet shield.


  • Ethernet shield attached to pins 10, 11, 12, 13

created 12 April 2011
modified 9 Apr 2012
by Tom Igoe


#include <SPI.h>
#include <Ethernet.h>

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac = {
0x00, 0xAA, 0xBB, 0xCC, 0xDE, 0x02

// Initialize the Ethernet client library
// with the IP address and port of the server
// that you want to connect to (port 80 is default for HTTP):
EthernetClient client;

void setup() {
// Open serial communications and wait for port to open:
// this check is only needed on the Leonardo:
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only

// start the Ethernet connection:
if (Ethernet.begin(mac) == 0) {
Serial.println(“Failed to configure Ethernet using DHCP”);
// no point in carrying on, so do nothing forevermore:
for (;:wink:
// print your local IP address:
Serial.print(“My IP address: “);
for (byte thisByte = 0; thisByte < 4; thisByte++) {
// print the value of each byte of the IP address:
Serial.print(Ethernet.localIP()[thisByte], DEC);

void loop() {

I don’t have the original Mac address but this produces an ip and then I’m not able to connect to it.

I can't find a web page with that DuinoTECH ethernet shield. Can you provide a link to it?

Hi Duinotech for some reason doesn’t have a website?
So no help there.


Take a look at the square chip on the shield that says WIZnet. Does it say W5100? There are a couple different WIZnet chips on these shields and if it's a W5200 or W5500 then you just need to use a different library.

It says Wiznet 5100 but the troubling thing is I got it to work once but not again?


Try using the ChatServer example under File > Examples > Ethernet to see if that gives you different results.