When the new ControlSurfaceLanReachable preference is on, both the REST/WebSocket control surface and the OSC bridge bind to all interfaces (http://+:port/ via HttpListener wildcard, IPAddress.Any for OSC) instead of loopback. The settings VM persists the toggle, restarts both surfaces when flipped, and surfaces a ControlSurfaceUrl computed from the first non-loopback IPv4 + a Copy button so operators can paste the URL onto a control PC.
Use case: a headless host PC runs Teams + TeamsISO; a thin client on the same LAN drives it via /ui or a Stream Deck. Closed-network deployment, no auth — documented as a trusted-LAN-only mode in docs/CONTROL-SURFACE.md, including the one-time 'netsh http add urlacl url=http://+:9755/ user=Everyone' requirement and the firewall rule.