DNS Leak with a VPN: Detection & Fixes (2026)

DNS leaks are one of the most common ways a “connected” VPN setup can still reveal sensitive metadata. A leak doesn’t necessarily expose the content of what you read — but it can expose which domains you visit and when, which is often enough for profiling, filtering, or correlation.

The good news: you can catch most leaks quickly with a simple routine and fix them with a small set of settings. The key is to test at the moments leaks usually happen: after updates, after sleep/wake, and after network changes.

Quick checklist (60 seconds)

• Connect VPN → run DNS test → confirm you don’t see ISP/hotspot DNS.
• Run IPv6 test → confirm IPv6 is protected or intentionally disabled.
• Run WebRTC test in your main browser → confirm it doesn’t expose a real public IP.
• Enable a proper kill switch → repeat after sleep/wake.
• Repeat after switching Wi-Fi ↔ hotspot or after a VPN/OS update.

Why DNS leaks happen (and when they’re most likely)

In real life, leaks are rarely “always on”. They often show up at transition points: after an OS/VPN update, after sleep/wake, or when changing networks. Windows is the most common culprit due to adapter priority, caching and fallback behaviour.

If you frequently use cafés, hotels or trains, combine this with VPN on public Wi-Fi and the Wi-Fi security checklist.

How to test DNS, IPv6 and WebRTC (a repeatable routine)

Do it like a mini lab: baseline without VPN, then with VPN, then after a reboot. This catches intermittent leaks that otherwise stay hidden for weeks.

If you’re optimising your setup generally, see optimal VPN settings and VPN protocols. Some speed tweaks (like split tunnelling) can also make leaks more likely.

Fixes by device: Windows, macOS, Android, iOS and routers

The goal isn’t “more settings”. The goal is less randomness. Start with kill switch + DNS protection, then handle IPv6 and browser features.

Windows (most common leak point)

• Enable DNS leak protection inside the VPN client (if offered).
• Enable a proper kill switch and retest after sleep/wake.
• After changes, flush DNS: ipconfig /flushdns
• If your VPN doesn’t securely handle IPv6, disable IPv6 or use an IPv6-safe VPN configuration.

macOS

• Enable DNS protection + auto-reconnect/always-on mode if available.
• Check DNS state: scutil --dns
• If leaks appear after sleep, reconnect VPN and retest.

Android

• Enable “Always-on VPN” and “Block connections without VPN” (when available).
• Be careful with split tunnelling: keep it off unless you really need it.
• Retest after switching between Wi-Fi and mobile networks.

iOS

• Prefer reputable official VPN apps and keep them updated.
• After long idle periods, retest — leaks can happen around reconnect moments.
• If profiles get messy, reinstall the VPN profile (see iPhone VPN setup).

Routers

• VPN on the router is great for Smart TVs and consoles (see router VPN setup).
• Set router/DHCP DNS to prevent devices falling back to ISP DNS.
• If you don’t need IPv6, disabling it on the router can eliminate common leak paths.

Repeatable troubleshooting checklist

1. Connect VPN → run DNS/IPv6/WebRTC tests.
2. Enable kill switch → retest after sleep/wake.
3. Disable split tunnelling (for testing) → compare results.
4. Handle IPv6 + browser DoH/WebRTC → retest.
5. Restart router/device → retest (catches intermittent leaks).

FAQ

How often should I test for leaks?

After initial setup, after OS/VPN updates, after sleep/wake issues, and whenever you change networks (home, work, public Wi-Fi).

Are free VPNs more likely to leak?

Often, yes — they may lack robust DNS enforcement and kill switch behaviour. If you’re comparing, see free vs paid VPN.

Is public DNS (1.1.1.1 / 9.9.9.9) enough?

It’s usually better than ISP DNS, but the ideal is DNS fully inside the VPN tunnel to reduce correlation risk.

What’s the fastest “first fix”?

Enable kill switch + DNS protection in your VPN app, then retest after sleep/wake.

Conclusion

DNS leaks are manageable if you treat testing as a habit, not a one-time task. A solid setup is: DNS protection + kill switch + clean handling of IPv6 and browser features. Retest on the days leaks actually happen — update day, network change day, and sleep/wake day.