This project will show you how to configure a Raspberry Pi 4 as a bridge, not as a router.

Why as a bridge? The students at my high schooll can access to internet using a wifi network or using a different ethernet network. However the wifi network has a lot of problems of stability. One of the solution we thought, was to use a Raspberry Pi configured as a bridge to allow temporary our wireless devices to access Internet while the problems of stability are fixed.

In other words, the Raspberry Pi would create a wifi network to access Internet through the ISP´s router of our stable ethernet network.

By definition, a bridge connects two local networks within a single domain, using Media Access Control (MAC) addresses to determine destinations. Bridge traffic is non-routable, meaning data cannot move outside of the joined networks, or domain.

Moreover, this project can be useful if you want to connect wireless devices to a wired network.

Of course, this instructable could be a good STEAM project for your IT students with the following tasks:

Use Tinkercad to design a box for the Raspberry Pi and the 5V charger
Install and configure the Raspberry Pi OS
Install and configure RaspAP
Mount the Ethernet to WiFi bridge
Test it

I hope be usefeul for somebody

Supplies

Raspberry Pi 4
USB-A to USB-C cable (8 inches)
5V 3A USB-C charger
Heatsink case for the Raspberry Pi 4

Step 1: Use Tinkercad to Design a Box

The goal of this task is to design a special box for the RaspBerry Pi 4, the charger and the USB-A to USB-C cable

Box (Raspberry Pi 4)

Step 2: Install and Configure the Raspberry Pi OS

Install Raspberry Pi OS using Raspberry Pi Imager

Download and install Raspberry Pi Imager to a computer with an SD card reader. Put the SD card you'll use with your Raspberry Pi into the reader and run Raspberry Pi Imager.

Download the latest version of Raspberry Pi Imager and install it. Then:

Connect an SD card reader with the SD card inside.
Open Raspberry Pi Imager and choose the required OS from the list presented.
Choose the SD card you wish to write your image to.
Review your selections and click on the Write button to begin writing data to the SD Card.

Step 3: Install and Configure RaspAP

RaspAP is feature-rich wireless router software that just works on many popular Debian-based devices, including the Raspberry Pi.

Update RPi OS to its latest version, including the kernel and firmware, followed by a reboot:

sudo apt-get update
sudo apt-get full-upgrade
sudo reboot

Set the WiFi country in raspi-config's Localisation Options: sudo raspi-config

Install RaspAP from your device's shell prompt:

curl -sL https://install.raspap.com | bash

The Quick installer will complete the steps for you.

After the reboot at the end of the installation the wireless AP network will be configured as follows:

IP address: 10.3.141.1
Username: admin
Password: secret
DHCP range: 10.3.141.50 to 10.3.141.254
SSID: raspi-webgui
Password: ChangeMe

Your AP's basic settings and many advanced options are now ready to be modified by RaspAP.

By default RaspAP configures a routed AP as its hotspot, but in this project we want to configure it as a bridge AP where our upstream router assign IP addresses.

To toggle bridged AP mode we have to do the following:

Using a web browser type the default 10.3.141.1 address (Username: admin, Password: secret)
In the RaspAP web interface, go to Hotspot > Advanced tab,
Slide the Bridged AP mode toggle
Configure your SSID, Channel, Wireless Mode and your Security Settings (see images)
Save settings
Restart hotspot

Once the Raspberry Pi 4 has been restarted, if you try to access the web interface in bridged AP mode, you will no longer be able to access RaspAP's web interface using the default 10.3.141.1 address. Instead, access RaspAP's web interface by entering your RPi's hostname followed by .local. By default this will look like raspberrypi.local.