[JOKE] Bon, alors,puisque personne ne veut m'aider, je me réponds tout seul. [/JOKE]
La réponse est dans la doc de systemd-resolved.
Il suffit de remplacer le fichier /etc/resolv.conf par un lien symbolique vers /run/systemd/resolve/resolv.conf
cd /etc
sudo mv resolv.conf resolv.conf.sav
sudo ln -s /run/systemd/resolve/resolv.conf resolv.conf
Et le tour est joué.
Maintenant, un "cat /etc/resolv.conf" me donne :
jean-marie@serveur:~$ cat /etc/resolv.conf
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 2001:910:800::40
nameserver 2001:910:800::12
jean-marie@serveur:~$
Et je dois gagner du temps sur les requêtes DNS puisque le système ne cherche plus à interroger 127.0.0.53.
Amicalement.
Jean-Marie