I have a WebRTC application that streams video over LAN network and it works when both peers are connected to a wifi.
The issue is that when one peer runs a hotspot and the other peer connect to it I see no video.

but I get this error in the browser.

WebRTC: ICE failed, add a STUN server and see about:webrtc for more details 

I have no idea why I need a STUN server in this case even though it's a local network.
Is there an approach to avoid using a STUN server ?