Below are listed the most common game consoles and how to discover their wired MAC address. For other devices such as Smart TVs or home routers you should refer to the user manual, or check for any labels on the device.

Sony Playstation 3

On the cross media bar (XMB)
Goto Settings > System Settings > System Information The MAC Address is the first item listed

Sony Playstation 4

On the cross media bar (XMB)
Goto Settings > Network > View Connection Status
You want the MAC Address (LAN Cable)

Sony Playstation 5

Goto Settings > System > System Information
You are looking for MAC addresses for LAN (Ethernet)

Microsoft XBox 360

Goto System > Network Settings > Wired Network
Select Configure Network then the Additional Settings tab
Highlight Advanced Settings
Select Advanced Settings and copy the MAC address

Microsoft XBox One

Press the Menu button on your controller
Goto Settings > Network > Advanced Settings
The MAC Address is labeled Wired MAC

Microsoft XBox One X

At the dashboard goto Systems > Settings
Select Network Settings > Configure Network
At the bottom of the screen you want the Wired MAC Address

Nintendo Wii

Requires a Nintendo Wii LAN Adapter

Press the A button to go to the main menu
Select the Wii button
Select Wii Settings and scroll to the second page
Select Console Information
Look for the LAN Adapter MAC Address

Nintendo Wii U

Requires a Nintendo Wii LAN Adapter

From the Wii U Menu
Select System Settings > Internet > View MAC Address

Apple TV

The MAC address is listed on the UPC label as Ethernet ID OR you can get the MAC address from the device

From the main menu
Select Settings > About and look for Ethernet Network