It says:

“Tailscale is zero config VPN that creates a secure network between your Umbrel and your other devices. Even when separated by firewalls or subnets, Tailscale just works. Tailscale will assign your Umbrel a stable IP and an auto-assigned domain that stays consistent, no matter what network your Umbrel is connected to. It’s like a local network that works everywhere. Tailscale builds on top of WireGuard®’s Noise protocol encryption, a peer-reviewed and trusted standard.”