Ard Ethernet Dhcp

In this tutorial, you'll learn about Arduino DHCP Lease Renewal Fails. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

The Problem

Ethernet loses IP address after the DHCP lease expires.

Quick Fix

Wrong

Ethernet.begin(mac);  // No lease renewal handling

IP address lost after lease timeout (usually 24 hours).

Right

#include <Ethernet.h>

byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
unsigned long lastDhcpCheck = 0;

void checkDHCP() {
  unsigned long now = millis();
  if (now - lastDhcpCheck > 60000) {  // Every 60 seconds
    lastDhcpCheck = now;
    if (!Ethernet.maintain()) {
      Serial.println("DHCP OK");
    } else {
      Serial.println("DHCP renewed");
      Serial.print("New IP: ");
      Serial.println(Ethernet.localIP());
    }
  }
}

void setup() {
  Serial.begin(9600);
  if (Ethernet.begin(mac) == 0) {
    Serial.println("DHCP failed");
  }
  Serial.print("IP: ");
  Serial.println(Ethernet.localIP());
}

void loop() {
  checkDHCP();
}

DHCP OK
DHCP renewed
New IP: 192.168.1.101

Prevention

Ethernet.maintain() handles DHCP lease renewal. Call it periodically (every 30-60 seconds). It returns a status code: 0 = unchanged, 1 = renew failed, 2 = renew success, 3 = rebind failed, 4 = rebind success. Some firewall rules may block DHCP renewals.

DodaTech engineers apply these same patterns across Doda Browser, DodaZIP, and Durga Antivirus Pro for production IoT reliability.

FAQ