Ubuntu 20.04.3 LTS freezes, requiring a hard reboot
Solution 1:
From the comments...
Lenovo Legion 5 17IMH05H with Nvidia NV168 graphics card.
Note: X server was crashing with nouveau.
Note: memtest ran fine.
Note: BIOS updated to efcn52ww.
Updated to Nvidia driver 470 and so far it's running fine.
Also do:
sudo apt update
sudo apt upgrade