---
title: "W5500 server sends RST/ACK on connect request"
url: "https://maker.wiznet.io/forum/13685"
markdown_url: "https://maker.wiznet.io/forum/13685/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "Giorgi Tsintsadze"
created: "2020-02-06T15:02:19+09:00"
last_activity: "2020-02-10T08:25:10+09:00"
language: "en"
views: 966
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5500 server sends RST/ACK on connect request

## Question

Asked by Giorgi Tsintsadze on 2020-02-06 in Ethernet Chips.

Greetings.

I have been troubleshooting W5500. I have come across weird things.

When W5500 operates as server (socket status = 0x14) when it gets SYN packet it sends back RST/ACK instead of establishing connection.

when W5500 acts as a client, my PC does exactly the same.

sadly I cannot include pictures due to rules of this forum.
I also tried turning firewall off.

## Replies

### Reply 1 by Giorgi Tsintsadze, 2020-02-10

Hello

As it turns out you were right! thanks for pointing out.

if everyone is wondering I had my server at 9999 but I wrote 99 and 99 in port registers of W5500 resulting in actual pirt bumber of 25443 ![:slight_smile:](https://emoji.discourse-cdn.com/twitter/slight_smile.png?v=12)

thank you

---

Source: https://maker.wiznet.io/forum/13685