Raspberry Pi 4 b

Boot without Ubuntu gui

Not working: not loading ssh or ping or networking by default

systemctl set-default multi-user

Pi OS GPU memory

If you manually override the maximum in the GUI, the Pi won't boot anymore

Mount external hard drive in /etc/fstab

Pi will not boot if your drive is not plugged in, unless: nofail,x-systemd.device-timeout=10000ms

Pi-Hole

Configurations

for a clean Query Log with names, add IPs in /etc/hosts