---
title: "W5300 Network adapter disconnect issue using TCP protocol with Intel's I350 network card"
url: "https://maker.wiznet.io/forum/15762"
markdown_url: "https://maker.wiznet.io/forum/15762/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "a6680345"
created: "2025-06-13T16:13:22+09:00"
last_activity: "2025-06-16T13:57:49+09:00"
language: "en"
views: 5
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5300 Network adapter disconnect issue using TCP protocol with Intel's I350 network card

## Question

Asked by a6680345 on 2025-06-13 in Ethernet Chips.

Hi

I am currently using your company's W5300 chip for circuit board design and controlling it with an FPGA. Hower, I have encountered an issue. We are using the TCP protocol. When we configure the W5300 to 10M, and test its communication with a network debugging assistant, the connection of the network adapter remains established without any change when the network is disconnected. But when we configure the 5300 to 100M, when we click to disconnect the network debugging assistant, the network adapter will show that the network cable has been unplugged and needs to be re-identified for connection. This phenomenon exits in INTEL'' I350 network card. Could you offer some suggestions for us here? Many thanks!

## Replies

### Reply 1 by Lihan__, 2025-06-16

Thanks for your detailed description. Before we look into this further, could you help clarify a few points?

1. When you mention "Network Debugging Assistant", are you referring to a PC software tool (like a TCP test tool), or a separate hardware device?

2. When you say you "disconnect the Network Debugging Assistant", what exactly happens? Are you just closing a TCP socket, or does the tool actually disable the network interface or simulate unplugging?

3. You mentioned that this issue "exists in the Intel I350 network card"
does this mean the same behavior occurs when using an I350, or that you're testing with I350 in this setup?

4. Is the W5300 connected directly to the Intel I350 NIC, or was I350 tested separately in a different configuration? With these clarifications, we can better understand the setup and provide a more accurate suggestion. Thanks!

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Source: https://maker.wiznet.io/forum/15762