GRE Tunnel Question

Centmin Mod is provide as is, so short of scripted related bugs or issues, any further optimisation to the web stack components - nginx, php-fpm, mariadb mysql, csf firewall etc or web app specific configurations are left to the Centmin Mod user to deal with. So I do not provide any free support for such.

However, Centmin Mod users are free to help each other out and ask questions or give answers on this community forum. My hopes are that this community forum evolves so that more veteran long time Centmin Mod users help new Centmin Mod users out

With that said, the BuyVM instructions are what you need to do, just with CSF Firewall in place the iptable rules you might need to put them into a manually created shell bash script at /etc/csf/csfpre.sh for them. Rest is up to you and other suggestions by forum members.