Dual display is not working on Ubuntu 20.04

Applies to: Ubuntu 20.04

Issue Summary

Ubuntu 20.04 uses an older Kernel version 5.15.0, which does not support dual display via HDMI and Dual Display. To enable this functionality, install kernel 7.1.7 using the Mainline Ubuntu Kernel Installer.

Resolution

IMPORTANT: Before proceeding, verify your current kernel version, 
as these instructions apply only to Kernel version 5. To check the 
Kernel version, run the $ uname -a command.

To install Kernel 7.1.7:

1. Open a terminal and run the following commands to install the Mainline Ubuntu Kernel Installer:
   
   $ sudo add-apt-repository ppa:cappelikan/ppa
   $ sudo apt update && sudo apt upgrade -y
   $ sudo apt install -y mainline
    
2. After installation, launch Mainline from the application menu.
   
   
   

   NOTE: When you launch Mainline for the first time, it will take 
   a while to fetch the latest kernel PPA information.

    
3. Select version 6.11.7 from the list, then click Install.
   
   
    
4. Press F2 while rebooting your system to apply the change.
    
5. Locate Disable SecureBoot (often under Security > Boot, or Advanced settings) and toggle the switch to OFF.
    
6. Save the changes and exit the BIOS.
   
   
    
7. In the navigation tree on the left side of the screen, select Settings > Display.
   
   Both HDMI and Dual Display displays are now available.
   
   
    
8. Run the following command to verify the current kernel version: $ uname -a