Using the url https://salamandar.fr/baikal/dav.php (or basically any url, direct addressbook url,…), i got an error (“Aucun accès possible au service CalDAV ou CardDAV” in french).
By the looks of the logs, Davx5 fails while “trying to determine principal from initial context path=https://salamandar.fr”. I did provide the correct credentials, it connected successfully to Baikal and even got my full name and email… before failing on this weird test.
EDIT: I manually modified my old config (not the same domain name) to match the new domain name, and it works perfectly. I guess the initial config should not try to access the root of the domain name.