RTSP does NOT require internet connection, so that is the only way to do LAN only. It makes no sense that the non-RTSP mode requries internet connection, this is one of the reasons i don’t like this camera, it phones home to china and you can’t do nothing about it. Even with a firewall if you enable it then the camera can’t connect to “initiate” the connection.
RTSP is an option, but the problem is that is capped @ 10 fps and the lag is significant, about 5 seconds.
I am about to return these cameras back to Amazon, As i dont see a path with such a poor FPS in LAN only mode. It is a shame that you can’t run the app in LAN only mode with the native app