apache2 only VPN

[Ho2x]

Good morning,

thank you for the script!
I need your light,
I have good access to my apache2 port 80 from my local ip through the vpn.
however, I would like apache2 to be accessible only when connected to the vpn.
For the moment I still have access from the public ip or the domain name.

I tried with iptables rules and config in an apache2 VHOST but for the moment impossible, either I have no access at all, or back to square one (Available from the VPN and from the WAN)

An idea ?
THANKS !