Install the tlp package:

sudo apt install tlp

Turn WiFi off:

wifi off

Turn WiFi on:

wifi on

Toggle WiFi:

wifi toggle

It would have been nice if we had a wifi restart command that ran wifi off, waited a few seconds and then ran wifi on. I’ve added a ZSH alias to do this (you can do a similar thing in bash):

alias wifi-restart="wifi off && sleep 1s && wifi on"