The Pocket LAN Tester Kit is a small portable Ethernet diagnostic tool designed for quick LAN troubleshooting. The goal is to create a simple handheld device that can be plugged directly into an Ethernet port and immediately show whether the network connection is working.

Instead of carrying a laptop or using an expensive professional network tester, this device gives the most important basic network information directly on a small OLED display.

What it does

The device checks the basic things you usually need when testing a LAN connection:

• Ethernet link status
• DHCP availability
• Assigned IP address
• Gateway address
• DNS server
• Basic internet connectivity

This makes it useful for testing network ports, routers, switches, patch panels, classrooms, workshops, homelabs, server racks and general electronics/networking projects.

Why I built it

When working with Ethernet connections, I often wanted a small tool that could quickly answer a simple question:

“Does this LAN port actually work?”

A laptop can do this, but it is not always convenient. Professional LAN testers are useful, but they can be expensive and often do much more than needed for simple everyday checks.

The idea behind this project is to build a small, affordable and DIY-friendly network tester that focuses on the most useful checks.

Hardware concept

The current prototype is based around a microcontroller and a W5500 Ethernet controller. The W5500 handles the Ethernet interface and communicates with the microcontroller over SPI.

A small OLED display is used to show the test results. The device has a simple button-based interface and is built into a compact 3D printed enclosure.

Main hardware blocks:

• Microcontroller
• W5500 Ethernet controller
• RJ45 Ethernet connector
• OLED display
• Push button
• USB-C or battery power input
• Custom PCB
• 3D printed enclosure

The enclosure is designed to be pocket-sized and easy to carry, while still leaving space for the display, button and Ethernet connector.

Firmware

The firmware initializes the display and Ethernet controller, then runs the network test sequence.

Basic firmware flow:

1. Start device
2. Initialize OLED display
3. Initialize W5500 Ethernet controller
4. Check Ethernet link
5. Request network configuration using DHCP
6. Display IP address, gateway and DNS
7. Test basic internet connectivity
8. Show the final result on the OLED display

The user interface is intentionally simple. The device should be easy to use even without technical knowledge: plug in the cable, press the button and read the result.

Open source

This project is planned to be open source.

The goal is to publish firmware, documentation, schematic information and design files so other makers can learn from it, modify it and build their own version.

I want this project to be useful not only as a finished device, but also as a learning project for Ethernet, embedded programming, PCB design and network diagnostics.

Buy / support the project

You can buy or support the Pocket LAN Tester Kit here: [https://www.kickstarter.com/projects/lan-tester/pocket-lan-tester-kit?ref=user_menu]

The first version is planned as a DIY electronics kit. It is made for makers, students, homelab users and people who want a small practical Ethernet troubleshooting tool.

What this project is not

This device is not meant to replace expensive professional cable certification testers.

It does not certify Ethernet cables according to professional standards. Instead, it focuses on basic practical diagnostics:

• Is there a link?
• Does DHCP work?
• Did I get an IP address?
• Is the gateway reachable?
• Is DNS configured?
• Is internet access working?

For many everyday situations, these checks are already enough to find the problem quickly.

Project goal

The goal of the Pocket LAN Tester Kit is to make Ethernet troubleshooting faster, cheaper and more portable.

It should be simple enough for students and makers, but still useful enough for real troubleshooting in workshops, schools, homelabs and technical environments....