What happens when you try to navigate to adm.name.dyndns-ip.com?
I suggest creating individual vhost files for each servername. This can make diagnosing and maintenance easier. With individual vhost files you can enable and disable on site at a time.
For sites on the same machine you should use localhost, like:
You should not need to duplicate servername and serveralias when they are equal.
One other setting which can help when forwarding to another machine is to perserve the url with:
I suggest you move:
Also you should not need the following in your vhost file. These are global mods loaded once with "sudo a2enmod proxy" or similar.
LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so
LoadModule proxy_connect_module modules/mod_proxy_connect.so