Do you remove the Nextcloud to another software? I hope not.
The url
https://monnuage.ac-versailles.fr redirects to
Arrêt de Monnuage
and that looks like Nextcloud and then redirect to a SSO-service hopefully for nextcloud.
I think if you only change the name you must:
- change the nextcloud in all nextcloud-apps (android, iOS) all users
- change server settings config/config. php (to the new server name)
- configure SSO if not configured
The old and new nextcloud serves are on the same system (185.53.177.50).
Is this the same nextcloud instance?
If all yes perhaps you can temporary use both names.