Klipper not connecting to the MCU

[Sineos]

@Debian Bullseye Bug causing Klipper to no longer find the printer board

• Execute sudo apt edit-sources
• In the editor that opens (if asked choose nano) add following line at the end:

deb http://ftp.debian.org/debian bullseye-backports main non-free contrib

• Save and close
• Run: sudo apt update
• Closely monitor the output of the above command. On errors see the following post
• Run: sudo apt install udev -t bullseye-backports
• Reboot

What is missing? Does not look too complicated to follow these few steps,no?