issue with default vhost

Hello!

There is an Nginx instance on one of my VMs (192.168.56.101) and three (enabled) vhosts: "default" and two further vhosts I created.

When I enter the IP in my host browser or "localhost" in my guest browser, in both cases the default page (/usr/share/nginx/html/index.html) is displayed:

It works!
This is the default web page for this server.
The web server software is running but no content has been added, yet.

OK. Now I've edited the default page /usr/share/nginx/html/index.html. But I only can see the chages in the guest browser. So, no changes are visible, when access the defalt vhost via IP from the host system.

Furthermore I created a simple PHP file index.php

<?php
phpinfo();
?>

and added it to the default vhost directory (/usr/share/nginx/html). When I access it from the guest (localhost/index.php), it works fine. But when I try it from the host, only a message

File not found.

is displayed.

I only have this issue with the default vhost. The oher two are working fine.

What can be the cause? What do I do wrong?

thx