Tailscale is a bit more than a VPN. It operates in a mesh configuration rather than a traditional VPN concentrator setup. Tailscale's control plane orchestrates NAT traversal for devices on the Tailnet (through techniques like UDP hole punching) and allows them to establish direct Wireguard tunnels between them. That way, there's no VPN concentrator bottleneck because there's no concentrator at all, every device establishes tunnels to every other device.