Optional: Dynamic DNS

If you operate your Pi-hole + OpenVPN at home, it is very likely that you are sitting behind a NAT / dynamically changing IP address. In this case, you should set up a dynamic DNS record, which allows you to reach your server. You can exchange the address that has been configured during the setup of OpenVPN like this:

vim /etc/openvpn/client-common.txt

Look for the remote line and adjust it accordingly (remove IP address, add host name), e.g.

remote home.mydomain.de 1194

This change has to be repeated in each client config file (*.conf) that you have been created up till now.

If you have set up a DDNS domain for your IP address, you will likely need to add a host-record to Pi-hole's settings.

pihole -a hostrecord home.mydomain.de 192.168.1.10

If you don't do this, clients (like the Android OpenVPN client) will not able to connect to the VPN server when inside the internal network (while it will work from outside). Afterwards, the client will be able to connect to the VPN server both from inside and outside you local network.