For official docs on virtual hosting with apache:
https://httpd.apache.org/docs/2.2/vhosts/name-based.html
Main host goes away
If you are adding virtual hosts to an existing web server, you must also create a <VirtualHost> block for the existing host. The ServerName and DocumentRoot included in this virtual host should be the same as the global ServerName and DocumentRoot. List this virtual host first in the configuration file so that it will act as the default host.
Some other settings in httpd.conf (the main config for Apache) to check:
# Listen: Allows you to bind Apache to specific IP addresses and/or
# ports, in addition to the default. See also the <VirtualHost>
# directive.
Listen 80
### Section 3: Virtual Hosts
#
# VirtualHost: If you want to maintain multiple domains/hostnames on your
# machine you can setup VirtualHost containers for them. Most configurations
# use only name-based virtual hosts so the server doesn't need to worry about
# IP addresses. This is indicated by the asterisks in the directives below.
#
# Please see the documentation at
# <URL:http://httpd.apache.org/docs/2.2/vhosts/>
# for further details before you try to setup virtual hosts.
#
# You may use the command line option '-S' to verify your virtual host
# configuration.
#
# Use name-based virtual hosting.
# note ... this item is initially commented out
NameVirtualHost *:80
You said the 'other server' is in httpd.conf' …
could we have a look see?
As far as each Moodle config ... it's 'strict' and must match that of the virtual server config.
'spirit of sharing', Ken