problem adding new serwer - redirecting all http to new server

hello
has anyone encountered the problem as below:
I have a debian 8 + virtualmin 6.06 gpl server. I host several servers on it that work properly.
the problem occurs when I add a new server.
all http queries to already existing servers start to hit the newly added server / domain.
for example: I am adding newdomain.com. on the server I already have olddomain.org when I go to http://olddomain.org my query is directed to / home / newdomaincom / public_html - which generates error 403 due to lack of index.html
in the apache configuration I do not see any problem.
after https it seems that everything is working properly.
I found a similar topic in the beginners/newbie section, but without any specific answer.
temporarily I can not afford to restart the whole machine, which can solve the problem.

does anyone have any suggestions?

Has anyone encountered a similar problem?

I have the same problem. Have you managed to resolve this?

check how the configuration of your virtualhost in apache looks like.
for me, some entries were in the form VirtualHost *: 80 while the part in the form VirtualHost 123.123.123.123: 80 I do not know why, because all were added in the same way with the same options selected. I modified all entries to VirtualHost 123.123.123.123: 80 and everything started working properly. look how it looks at you. let me know please.

did it help?

Thank you @bartbl for your reply. Yes it works.
I’ve also stumbled upon this thread https://www.virtualmin.com/node/59694 that presents two solutions (one solution is the same as the on you suggested).