---
title: "W5100 send RST after receive ACK in 3-way handshake"
url: "https://maker.wiznet.io/forum/12450"
markdown_url: "https://maker.wiznet.io/forum/12450/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "Brzoza"
created: "2017-08-30T09:08:25+09:00"
last_activity: "2017-08-30T13:06:52+09:00"
language: "en"
views: 1011
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5100 send RST after receive ACK in 3-way handshake

## Question

Asked by Brzoza on 2017-08-30 in Ethernet Chips.

Hi All
I got problem with IP chipset W5100 in server mode.
Chipset is trying to connect to server, send SYN to server. Receive ACK and then send RST ![:frowning_face:](https://emoji.discourse-cdn.com/twitter/frowning_face.png?v=12)

Chipset IP 10.1.3.102, Server IP 10.1.3.104:

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/d/d62127be6190abc4c5ccdac7a1a9ecca170f9d9a.png) image1369×161 17.9 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/d/d62127be6190abc4c5ccdac7a1a9ecca170f9d9a.png)

Connection is establish due to TCP retranssmition but RST shouldn’t be send.
Please advice.

## Replies

### Reply 1 by Brzoza, 2017-08-30

Hi All
I fixed problem.
Source port was the same for all outgoing connection.
I changed it to random and problem disappeared.

Brzozoa

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Source: https://maker.wiznet.io/forum/12450