Send local IP from VPN instead of remote IP

Question

I'm trying to setup a server with L2TP and Apache. Some folders in the Apache config will only be accessible to those connected to the VPN.

I do know that I can use the allow and deny rules with the IP ranges, however it doesn't send the correct IP.

For example, my VPN has a local IP range from 172.16.255.2 - 172.16.255.254. In Apache I can set it to only allow IPs in 172.16.255., yet as soon as I try to access the page, it will show a 403 error along with a message in the error log with the IP of my home/office and access denied by server.

Do I need to make any changes in the VPN configuration or in dnsmasq?

Thanks a lot!