Hi,
> Actually it is a WAMPServer issue because...
NO.
Wampserver is delivered "out of the box" with a total ban of access from outside.
You have made changes to open the server from the outside; This is YOUR problem and absolutely no problem with wampserver.
If you do not have the ability to set up your modem / router, you must use a web host for your sites and develop them only locally.
One possibility exists. This is to leave for wampserver the total access ban (Require all denied) and declare all your local sites as VirtualHost and allow only a few IPs for VirtualHost.
However, without Port forwarding on the modem, this will not prevent access to your PC by everyone.
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Wampserver install files & addons