Things appear to have changed with both the Google Cloud Console and the PiVPN setup. I will be making some updates soon. The demand for Wireguard is much higher, so I will be focusing my efforts on getting a Wireguard guide drafted before coming back to this OpenVPN one.

Thanks for your contributions @rajannpatel and team, another minor yet annoying issue I encountered because I went into zombie copy paste mode, regarding the guide for your older repo OpenVPN + Pi Hole - the instruction for adding the NAT table rule. The rule "-A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE" is I'm guessing out of date since the default public interface created on my GCP vm was named "ens4". Verified this was what indeed what should have been used in the NAT rule based on your new setup.sh script where you pull the public nic info using the "ip -4 route ls | grep default | grep -Po '(?<=dev )(\S+)' | head -1" command. Not sure if this is also necessary but I saw that you enable port forwarding in your script so I also did that and it got everything up and running great.

Having the incorrect public ipv4 interface in the rule declaration resulted in no internet connection while Pi Hole worked fine :| Just throwing this out there in case someone else runs into the same issue. Thanks again for this, really awesome guide.

So when installing PiVPN you will be asked to choose a DNS Provider, we don't want to push any 3rd party DNS services to clients connecting via VPN. We want to push 10.8.0.1, which is our Pi-Hole DNS Server.

Pi-Hole can also act like a Router, and that is why during its installation you have the option of choosing a Custom Domain / Search Domain.

For whatever reason, PiVPN was unable to install and would exit the installer before I could get to the prompt for DNS provider. Based on your comment above with changes in GCP with PiVPN, I assume this could be part of the issue. I had to improvise a bit and followed some parts of the guide here - https://docs.pi-hole.net/guides/vpn/overview/.

Side note - your Pi Hole + Wireguard config script is great and it did work for me, but I realized that Windows users must have admin privileges to run WG client, and not all my users necessarily have that. Thus had to go this route. It's working great so far. Thanks again.

I will run through the steps again tonight and figure out what may have changed, thanks for the heads up!