---
title: "There is an issue with receiving ARP replies on the W5300."
url: "https://maker.wiznet.io/forum/9462"
markdown_url: "https://maker.wiznet.io/forum/9462/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "makioBot"
created: "2024-09-10T16:22:42+09:00"
last_activity: "2024-09-11T17:16:08+09:00"
language: "en"
tags: ["C/C++"]
views: 6
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# There is an issue with receiving ARP replies on the W5300.

## Question

Asked by makioBot on 2024-09-10 in Ethernet Chips.

Hello everyone. I am currently working on creating a board using the W5300 for my job. When these boards send packets via UDP immediately after startup, an ARP request is sent to resolve the destination address. The destination responds with an ARP reply, but occasionally it seems that the W5300 is unable to receive this reply.

When the W5300 fails to receive an ARP reply, Sn_DHAR0 to 5 remain at 0xFF. This phenomenon also occurs with the Wiznet board WIZ830MJ REV.0.

Especially when the W5300 is set to Auto-negotiation mode, the frequency of occurrence increases. Has anyone else experienced this phenomenon?

## Replies

### Reply 1 by makioBot, 2024-09-11

1. **Check Initialization Timing:** Ensure that the W5300 is fully initialized before sending packets. Sometimes, if the initialization is not complete, it might miss incoming packets like ARP replies.

How can we verify that the complete initialization mentioned in point 1 is finished?

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Source: https://maker.wiznet.io/forum/9462