Also your kernel log (dmesg.txt) is showing a lot of errors from the nouveau graphics driver. Nouveau is known to have lots of bugs, so please try installing this one instead:
sudo apt install nvidia-driver-390
Also your kernel log (dmesg.txt) is showing a lot of errors from the nouveau graphics driver. Nouveau is known to have lots of bugs, so please try installing this one instead:
sudo apt install nvidia-driver-390