---
title: "W5500 NOT WORKING"
url: "https://maker.wiznet.io/forum/16187"
markdown_url: "https://maker.wiznet.io/forum/16187/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "nbabu0001"
created: "2026-10-28T04:04:09+09:00"
last_activity: "2026-10-28T04:04:09+09:00"
language: "en"
tags: ["W5500"]
views: 0
replies: 0
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5500 NOT WORKING

## Question

Asked by nbabu0001 on 2026-10-28 in Ethernet Chips.

![](https://maker.wiznet.io/upload/ckeditor5/f34c20516a984818b0d03e4084962864.png) W5500 SPI interface appears to be functioning correctly, but the Ethernet PHY is not establishing a network link. The RJ45 ACT and FDX LEDs are not illuminating, and the Ethernet link remains down.

**Hardware and Test DetailsEthernet controller:** W5500

**Microcontroller:** Arduino UNO R4 Minima

**Ethernet connector:** TE Connectivity 2301995-2 integrated-magnetics RJ45 jack (MagJack)

**SPI connections:** MISO – D12, MOSI – D11, SCK – D13, CS – D10

**Supply voltage:** 3.3 V

**Network:** Known-working router and Ethernet cable

I tested the same Arduino, router, and Ethernet cable using a standard Arduino Ethernet Shield, and the connection worked correctly. However, the custom PCB does not establish a link.

**Diagnostic Results**

The W5500 responds correctly over SPI.

The VERSIONR register reads `0x04`, confirming communication with the W5500.

The PHYCFGR register reads `0xBA` in my direct register test, although the reported link status is DOWN.

The Ethernet library reports that the W5500 is detected, but DHCP initialization fails.

The RJ45 ACT and FDX LEDs remain off when the Ethernet cable is connected.

The custom board's Ethernet PHY does not establish a link, despite using the same cable and router that work with the standard Ethernet Shield.

I am investigating whether the issue could be related to the PHY configuration, the integrated magnetics in the TE 2301995-2 MagJack, the TX/RX differential-pair connections, center-tap circuitry, termination components, or another hardware-design requirement.

**Could you please advise on the following?**

What diagnostic procedure would you recommend to determine why the W5500 PHY is not establishing a link when SPI communication is working?

Are there specific W5500 PHY configuration registers or hardware signals I should verify?

Are there any particular requirements for the TX/RX differential pairs, center taps, termination resistors, or capacitors when using an integrated-magnetics RJ45 jack?

Could you review the W5500 reference schematic and advise whether there are common hardware-design mistakes that would cause this symptom?

---

Source: https://maker.wiznet.io/forum/16187