Strange one with an old virtual server

I have had an server (server02.servermanagement.com)i ran several websites on. It has had an quite old virtualmin software running. It was that version, which used the first server (123.com) as standard website. Lateron i moved this one together with others to another server (server04.servermanagement.com is the servers FQDN, there is no virtualmin virtual server for this one), Unfortunately, it still keeps this behaviour, so if i want to access the website of server04.servermanagement.com, it shows me the 123.com website, what ever i put in the /var/www/html folder won’t be shown, because 123.com interferes with that.

server02.servermanagment.com has been upgraded over time. I remember, that there was an option somewhere for standard webpage, but i cannot find it anymore.

Server04.servermanagement.com is also running on current webmin/virtualmin combo.

So, what are my options?

Thanks and best