Firefox has historically taken a somewhat more configurable approach to privacy settings than some competitors, including around WebRTC — testing your specific setup first clarifies whether Firefox's defaults are already handling things correctly for you.
Test before changing anything
Before adjusting any Firefox setting, run NetRiskScan's WebRTC Leak Test with your VPN active to establish whether a leak actually exists in your current configuration. Firefox's default behavior, combined with your specific VPN client, may already be handling this correctly.
Firefox's media peer-connection settings
Firefox exposes some WebRTC-related configuration through its advanced settings interface, giving more granular control than a simple on/off toggle in some other browsers. Changing these settings can affect how much address information Firefox exposes during connection setup — worth adjusting deliberately rather than as a blanket precaution, since more restrictive settings can also affect legitimate WebRTC-based calling functionality.
Privacy vs. compatibility tradeoffs
The more aggressively you restrict WebRTC candidate gathering, the more likely you are to encounter compatibility issues with legitimate video-calling or collaboration tools that rely on WebRTC working normally. This is the same tradeoff every browser faces — see Should You Disable WebRTC? for how to think about it.
Confirming a change worked
After any settings change, re-run the leak test to confirm the specific exposure you were addressing is actually resolved, rather than assuming a setting change had the intended effect.
FAQ
Does Firefox's Enhanced Tracking Protection affect WebRTC?
It's a separate feature focused primarily on cross-site tracking technologies rather than WebRTC's connection-setup behavior specifically — don't assume it addresses WebRTC leak concerns on its own.