Xampp works locally but Server 403 Error when trying to access it externally

Question

I am trying to set up Xampp on a USB pen (drive Z:) and have configured it to run dynamic VHosting and have added the domains to the host file on my PC.

"Z:\xampp\apache\conf\extra\httpd-vhosts.conf" shown below.

<VirtualHost *:80>
    UseCanonicalName Off
    ServerAlias *
    VirtualDocumentRoot "Z:/htdocs/%0"
    VirtualScriptAlias "Z:/htdocs/%0"
    LogLevel debug
    <Directory "Z:/htdocs/">
        Options Indexes FollowSymLinks
        AllowOverride All
        Order Allow,Deny
        Allow from all
   </Directory>
</VirtualHost>

"C:\Windows\System32\drivers\etc\hosts" shown below.

127.0.0.1        gallery
127.0.0.1        dashboard
127.0.0.1        club

I have a few sites in "Z:\htdocs\" in separate folders 'gallery', 'dashboard' and 'club'. All these work 100% fine; when I access them locally using 'http:/gallery/', 'http:/dashboard/' and 'http:/club/'.

The problem starts when I try to access them externally.

I have the No-IP DUC installed and working with the No-IP site, and the hostnames I have setup 'gallery.host.no-ip', 'dashboard.host.no-ip' and 'club.host.no-ip' do point to my IP address.

I have configured port forwarding on my BT Home Hub 5 so that all ports point to my PC and have used "http://www.yougetsignal.com/tools/open-ports" to ensure that they are open. I get green flags for all ports with the three different hostnames I have set up.

I have created folders for thees three hostnames in my "Z:\htdocs\" directory and copied all site content across.

"Z:\htdocs\" directory tree shown below.

> Z:\htdocs\

    > club
        > club.html
        > etc.

    > club.host.no-ip
        > club.html
        > etc.

    > dashboard
        > dashboard.html
        > etc.

    > dashboard.host.no-ip
        > dashboard.html
        > etc.

    > gallery
        > gallery.html
        > etc.

    > gallery.host.no-ip
        > gallery.html
        > etc.

So in theory I should be getting the same three sites locally or externally.

BUT EXTERNALLY

I get a Server 403 Error - Access forbidden!

I have been trying to fix this problem for two days now and have finally given up hope of fixing it myself, although I have fixed other problems along the way that have helped as it was just timing out before. I cant get this final Server 403 Error - Access forbidden do go away.

If anyone can help I would be very grateful.