Firefox DNS Leak and DoH Settings With a VPN

Firefox Enable DNS over HTTPS can conflict with VPN DNS. Configure it correctly for leak-free browsing. Firefox TRR / DoH modes Firefox can use DoH in off, max protection, or opportunistic modes. Max protection sends queries to the configured DoH provider and can bypass system/VPN DNS. Privacy trade-offs DoH hides DNS from the local network but shifts trust to the DoH provider. With a trusted VPN resolver, prefer system DNS via the tunnel. about:config keys Advanced users inspect network.trr.mode and related prefs. Document changes. Reset to defaults if sites break. Recommended VPN setup Connect AstraGuard → set Firefox DoH Off for strict VPN DNS → test → only re-enable DoH if it matches your threat model. Also check WebRTC Firefox DNS fixes do not stop WebRTC IP leaks. Harden both. See WebRTC fix guide . Firefox settings path Settings → Privacy & Security → Enable DNS over HTTPS. Choose Off for VPN-resolver preference, then confirm with a leak test. Advanced users can inspect network.trr.mode in about:config . Protect yourself with AstraGuard VPN AstraGuard VPN helps keep DNS inside the tunnel with strong encryption, kill switch options, and simple setup on desktop and mobile. Create an account , pick a plan on packages , then verify on privacy tools .