Require Network line of sight

Can we clarify if "network line of sight" means simply reachability, or does this mean that you must be on the same subnet.  These are two completely different things and could be equally called Line of Sight.

Network: Open WebUI must have network line-of-sight to the Home Assistant URL.
https://openwebui.com/posts/home_assistant_tool_4fc8e753

Thank you,
Russell