The post title is a bit of a mouthful but a necessary one – this is a very specific scenario. Using pfSense as a dedicated gateway/firewall on the OVH-network was already not a simple situation; doing it inside a KVM (with Proxmox VE as wrapper which will also host LXC’s on the ‘LAN’) adds another layer of complexity. This guide was pieced together from various tidbits all over the web and my own experimentation so I thought it a good idea to do a solid write-up on it – if not for posterity then for my own future reference.