WebRTC leak test
WebRTC can reveal your real IP address to a website even when a VPN is on. Run the test with your VPN connected.
If you see a leak
Compare the public address shown with the one on the IP page. If they differ, disable WebRTC in your browser (Firefox: media.peerconnection.enabled set to false) or use an extension that blocks WebRTC IP exposure. Local addresses such as 192.168.x.x are not a leak.