What is a WebRTC leak?
WebRTC lets browsers make video and voice calls directly. To connect, the browser finds out its own addresses and can share them with the page. With a VPN on, the address it finds should be the VPN's. If it finds your provider's address instead, any site can read your real IP: that's a WebRTC leak.
Local addresses
Modern browsers hide your local network address (like 192.168.1.20) behind a random name ending in .local. Seeing one of those is normal and not a leak.
How to stop a WebRTC leak
- Firefox: type about:config in the address bar and set media.peerconnection.enabled to false.
- Chrome, Edge, Brave: install Google's "WebRTC Network Limiter" extension, or in uBlock Origin's settings tick "Prevent WebRTC from leaking local IP addresses".
- VPN apps: many have a setting that blocks WebRTC leaks. Turn it on, then run this test again.