my W5100 can't get IP address from router

Hello guys, i have a problem. i want to connect w5100 to router to get ip address with Dhcpaddressprinter form ethernet library, but my serial monitor output is “Failed to configure Ethernet using DHCP” and i dont use a SD card. and the indicator from FULL D,100M,PWR is ON and the rx,LINK is blinking. i use straight cable and arduino uno
can you help me?

#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 = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };

// 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 native USB port 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:

void loop() {

switch (Ethernet.maintain())
case 1:
//renewed fail
Serial.println(“Error: renewed fail”);

case 2:
//renewed success
Serial.println(“Renewed success”);

//print your local IP address:

case 3:
//rebind fail
Serial.println(“Error: rebind fail”);

case 4:
//rebind success
Serial.println(“Rebind success”);

//print your local IP address:

//nothing happened


void printIPAddress()
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);


and i dont have a MAC address behind the w5100 hardware, so i try MAC Address form any forum to use it. thx

Insure your shield is plugged into the Uno fully. Check the solder joints on the ICSP connector pins.

Some w5100 shields have a manufacturing bug. They put the wrong resistor set on the shield, and it prevents the w5100 from communicating with the network.

i have the same problem

nsnt: i have the same problem

And did you try what SurferTim suggested? Do you have an original Arduino Ethernet Shield or a Chinese clone?