[Auto solved...] ESP32, W5500 and Ethernet.h - no DHCP, no visibility in network

I am trying to get an ESP32 DevkitC V4 to run with a W5500 module - I need a wired Ethernet connection unfortunately. The code (stripped to the relevant parts) is like this:

// SPI for W5500 Ethernet module
#include <SPI.h>
#include <IPAddress.h>
#include <Ethernet.h>
// Variables for Ethernet.h
byte mac[] = { 0x30, 0x2B, 0x2D, 0x35, 0x51, 0xA2 };  
IPAddress ip(192,168,178,141);
IPAddress myDns(192,168,178,1);
IPAddress gateway(192,168,178,1);
IPAddress subnet(255,255,255,0);
// start the Ethernet connection:
  Serial.println("Trying to get an IP address using DHCP");
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // Check for Ethernet hardware present
    if (Ethernet.hardwareStatus() == EthernetNoHardware) {
      Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
      if (Ethernet.linkStatus() == LinkOFF) {
        Serial.println("Ethernet cable is not connected.");
        // initialize the Ethernet device not using DHCP:
        Ethernet.begin(mac, ip, myDns, gateway, subnet);
  // print your local IP address:
  Serial.print("My IP address: ");

(this is basically the example code from the Ethernet.h library)

After power up, the yellow LED on the RJ45 jack starts blinking slowly. 30 seconds later the DHCP request is terminated and the according messages are printed:

Trying to get an IP address using DHCP
Failed to configure Ethernet using DHCP
My IP address:

Now the yellow LED is steadily on, the green traffic LED is signalling data traffic. But the device is not visible in the network at all (the router is an AVM Fritz.box).
I do not expect it to react on ping requests (no ICMP), but I thought it must be known to the router? And why does DHCP fail? It is working flawlessly with other devices in the network.


After resetting the W5500 several times it seems to work now without a change - heaven knows why.

Thanks for your attention anyway!

Voltage supply drop maybe? Reset line of the W5500 is floating? Try pulling it HIGH explicitly and adding a bypass cap on the 3.3V line for it…

Yes, will do. For the time being I am using the 3.3V line of the DevkitC, for two more modules as well. May be the current drain is too high at startup. There will be a separate power supply in the final prototype.