Static IP on OpenVPN server

I´ve managed to set up an OpenVPN server in my Gl-MT300N-V2 but the client´s IPs are dinamically assigned. I´ve been trying to make them static with no succes, apparently it´s necessary to change the server.conf file but I cant´find it anywhere…
I´ve tried to follow the last post of this topic:

thanks for any help

The server.conf is located in /etc/openvpn/ovpn/. You may use ccd file to arrange the static address.
Start the server and use following commands:

mkdir -p /etc/openvpn/ccd
touch /etc/openvpn/ccd/DEFAULT
echo ifconfig-push >/etc/openvpn/ccd/DEFAULT

( is the static ip you want to set)
Then add this line to /etc/openvpn/ovpn/server.conf:
client-config-dir /etc/openvpn/ccd

Then use /etc/init.d/vpn-service reload to reload the settings.

Thanks for your ultra fast repply!
First of all, I´d like to apologize for my ignorance, I was looking for a .conf file but according to the manual:
“Note that on Linux, BSD, or unix-like OSes, the sample configuration files are named server.conf and client.conf . On Windows they are named server.ovpn and client.ovpn .”
OpenWrt/GLinet routers use the .ovpn extension.