Hello, After I create a new virtual server with Virtualmin the access takes over other sites if they are accessed with http. It doesn't interfere if it is accessed via secure https.
So https://old-site-url >> Correct site.
My settings of apache are old and it now I am afraid to create any new site because it disturbed. They had been created via Virtualmin but when we secured the sites with letsencrypt the setting had been added manualy. I thing that it does confuse Virtualmin… Thank for any help. Ichi