EasyGeoIP

EasyGeoIP guide · Published July 24, 2026

IPv6 leaks: what they are and how to fix them

A VPN can protect IPv4 while leaving IPv6 on the ordinary ISP route. The result is not a mysterious browser trick: it is a second network path that the tunnel did not capture.

Run the IPv6 connection test

Why two protocols matter

Dual-stack networks support IPv4 and IPv6 at the same time. Applications ask DNS for available destinations and may prefer IPv6 when both options work. Protecting only IPv4 does not force the application to abandon IPv6.

If the operating system has a global IPv6 route outside the tunnel, a website with IPv6 support may see the ISP-issued IPv6 address while an IPv4-only checker displays the VPN exit.

How to recognize a leak

Connect the VPN and run an IPv6-specific test. Compare the network organization and country with the expected provider. An IPv6 address belonging to the original ISP while IPv4 belongs to the VPN is a strong leak indicator.

An unavailable IPv6 test is not automatically a failure. Some VPNs intentionally block external IPv6 when they cannot tunnel it safely. That is different from exposing the ISP route.

Common causes

Older VPN clients may create only an IPv4 tunnel. Manual OpenVPN or WireGuard profiles can omit IPv6 routes. Split-tunnel rules may cover selected IPv4 networks but not their IPv6 equivalents. Router-based VPN configurations often require separate firewall rules for each protocol.

Temporary reconnection windows also matter. When the tunnel drops, the system may immediately restore the ordinary route unless a kill switch blocks both protocols.

Preferred fixes

Enable the VPN application's IPv6 support or leak-protection setting and keep the client updated. Confirm that its kill switch covers IPv6. For manual tunnels, add the provider's IPv6 address and routes only when the service documents them.

If the provider does not support IPv6, disabling external IPv6 while connected is safer than allowing an unprotected route. Apply the change at the VPN or firewall layer when possible instead of relying on a browser setting.

Retest after every network change

Moving from home Wi-Fi to cellular data, waking a laptop, changing servers, or reconnecting after sleep can produce a different route. Test the active state, not only the first installation.

Save a local baseline in EasyGeoIP and compare the visible protocol and network after connecting. No test can replace a correctly configured kill switch, but repeatable observations reveal obvious routing mistakes.

Reference

Practical network privacy guides

How to check if your VPN is actually working Check whether your VPN changed your public IP, protects IPv6 traffic, and avoids browser leaks with a practical, evidence-based process. WebRTC leaks explained without the myths Run a WebRTC leak test, understand ICE candidates and mDNS masking, and learn when a browser result indicates a genuine VPN problem. Can websites see your real IP behind a VPN? Learn which IP websites normally see through a VPN, how leaks occur, and why accounts, cookies, and browser signals still identify users.