The local hostname and domainname are hardcoded as @mark_nl (great catch) found out here.
Ok, so to add the printers I try directly from cups in https without calling it from the gui?
Yes, exactly.
Thanks a lot to you and @mark_nl
You’re welcome. I changed solution to the post of @mark_nl because it’s the real solution with good description, I won’t have thought about the old GUI.
yes , ok