Realtek 5Gbe add-in NIC not appearing/not configurable in Ubuntu 22.04
This guide will cover how to fix the "Realtek 5Gbe add-in NIC not appearing/not configurable in Ubuntu 22.04" issue.
IMPORTANT: make sure you take note of the MAC address currently in use as this will be needed once the driver for the Realtek NIC is installed.
Scroll down and download the 5G Ethernet LINUX driver r8126 (for kernel up to 6.15).
Navigate to the folder you downloaded the driver to, right click on any empty space within the folder, and select "Open Terminal here".
Enter the following commands one at a time, pressing enter after each one.
tar -xzvf r8126-10.017.00.tar.bz2
cd r8126-10.017.00
sudo ./autorun.sh
If successful, you should be able to open Connection Properties, and there will be two different MAC addresses in the dropdown list.
Set the MAC address for Connection 1 as the one you wrote down from before Step 1.
Set the MAC address for Connection 2 as the other option in the list.
Once these are set, please test the connection by plugging in an Ethernet cable, if not already plugged in, and checking that the Realtek connection is transmitting data.
NOTE 1: If you do not see two different MAC addresses, please ensure that the last command in Step 3 was ran with sudo permissions
NOTE 2: As the driver is updated by Realtek, the file name will change to reflect the current revision, which will slightly change Step 3a and 3b. Please ensure you modify the command accordingly to match the file name.