You can use Tailscale to share a Factorio multiplayer server with friends — all without opening a port or touching a firewall rule. See how in our latest video https://tailscale.com/blog/factorio-multiplayer-video
Video: Share a multiplayer Factorio server over Tailscale
With the recent release of Factorio’s Space Age expansion, we’ve been playing a lot of the base-building game — and that started with setting up a multiplayer server and sharing it into our friends’ tailnets.