IPv6 Readiness Test
Find out whether your connection can actually use IPv6, which protocol your browser reaches for when both are available, and — if you do have an IPv6 address — whether it is quietly built from your network card’s hardware serial number.
Connectivity is measured against two independent third-party echo services. We do not log or store anything; the AAAA lookup runs over DNS-over-HTTPS from your browser.
Why this matters
The world ran out of IPv4 addresses years ago. The workaround was carrier-grade NAT: your provider gives you an address shared with dozens of other households, which breaks incoming connections, confuses geolocation, and means a neighbour’s behaviour can get your address blocked. IPv6 has enough addresses to give every device its own, permanently, and removes that layer.
Adoption is now substantial but far from universal, and it is wildly uneven between countries and between mobile and fixed networks. Mobile networks are often IPv6-first while the home broadband in the same country is not.
The privacy catch nobody mentions
With IPv4 behind NAT, every device in your home shares one public address. Sites see the household, not the device. IPv6 gives each device its own globally routable address — which means a site can distinguish your phone from your laptop without any cookie at all.
Older systems built that address out of the network card’s MAC address, embedding a hardware
serial number that never changes, even across networks. You could connect from home, from a café and
from an office, and the last half of your address would be identical every time. The test above flags
this if it sees it — look for ff:fe in the middle of the address. Modern operating systems
use randomised privacy extensions instead, and rotate them.
What each test means
IPv4 connectivity
Almost everyone passes. A failure here usually means an IPv6-only network using NAT64, which is increasingly common on mobile.
IPv6 connectivity
Tested against two independent endpoints so one being unreachable does not produce a false negative. Failing both means your network, your router or your provider is not carrying IPv6.
Which one your browser prefers
When a site has both, the browser picks. The standard says prefer IPv6, but Happy Eyeballs races both and takes whichever answers first, so a slow IPv6 path loses to a fast IPv4 one. Having IPv6 and still connecting over IPv4 usually means your IPv6 route is slower.
Address type
A global unicast address starting 2 or 3 is the real thing. Anything
starting fe80 is link-local and never leaves your network. fc or
fd is a private range. 2002: is 6to4 and 2001:0: is Teredo —
both are tunnels rather than native IPv6, and both are slow and largely abandoned.
What this can’t tell you
- Nothing about your local network’s internal IPv6. This sees only what reaches the internet.
- It cannot prove IPv6 is absent. A blocked request, a captive portal or a firewall looks identical to no IPv6 at all. Both endpoints failing makes it likely, not certain.
- Nothing about IPv6 performance. Working is not the same as fast, and a slow IPv6 path is a real cause of pages feeling sluggish.
- A VPN changes everything here. Many VPNs carry IPv4 only and leave IPv6 to leak around the tunnel — which is the whole point of the VPN leak test. If you are connected to one, test there instead.
Getting IPv6 if you do not have it
| Situation | What to try |
|---|---|
| Router has it switched off | Look for IPv6 in the WAN settings and set it to automatic or DHCPv6. The most common single cause. |
| Provider does not offer it | Nothing you can configure. Worth asking — many have it available but not enabled by default. |
| Works on mobile data, not at home | Normal. Mobile networks moved to IPv6 far earlier than fixed broadband. |
| You see a 6to4 or Teredo address | A tunnel, not native IPv6. Usually worth disabling — it is slower than plain IPv4. |
IPv6 is one of the addresses that can give you away.
VPN Leak Test What Is My IP DNS PropagationFrequently asked questions
Should I turn IPv6 off?
Generally no. Disabling it is folk advice left over from a decade ago when support was patchy, and it breaks things on modern networks. The exception is a VPN that does not carry IPv6 — there, turning it off prevents a leak, though a VPN that handles it properly is the better answer.
Why does my IPv6 address keep changing?
Privacy extensions, working as designed. Your system generates a temporary address, uses it for a while, then replaces it, so you cannot be tracked by address alone. A fixed address would be the thing to worry about.
Is IPv6 less private than IPv4?
In one specific way, yes: no NAT means each device is individually addressable rather than hidden behind one household address. Privacy extensions offset most of that. The old MAC-derived addresses did not, which is why this test looks for them.
My address starts with fd. Is that IPv6?
It is a unique local address — the IPv6 equivalent of 192.168.x. Fine inside your network, but it cannot reach the internet, so something else is carrying your traffic.