clear port 53

check that port is cleared

lsof -i :53

if bind9 is installed delete it

apt remove bind9

on ubuntu systemd-resolved uses port 53. So we stop this behavior.

emacs /etc/systemd/resolved.conf
DNSStubListener=no

and restart service

systemctl restart systemd-resolved

start pihole

run checks

# check that dns (pihole is working)
dig @188.165.217.148 -p 53 google.com

#check that internet is still ok
curl google.com

install it in the dhcp of the freebox

http://mafreebox.freebox.fr/

parametre
dhcp
DNS1: ip du serveur ou se trouve pihole

now every machine connecting to your wifi is adblocked