IPv6 problems usually come in three kinds: you have no IPv6 at all, you have an IPv6 address but the connection doesn’t work, or everything works but some sites load slowly. Start by finding out which one you have.
1. Test first
Run the IPv6 test. It sends one request to an address with only IPv4 and one to an address with only IPv6.
- Both work — your connection is dual-stack and IPv6 works.
- IPv4 only — you have no working IPv6. Read on.
- IPv6 only — unusual at home; you are probably on a mobile network with NAT64.
2. Does your device have an IPv6 address?
Check the device’s network settings (ipconfig on Windows, ifconfig or System Settings on a Mac).
- If you only see addresses starting with
fe80:, the device has only a link-local address. That isn’t enough for the internet — the router isn’t handing out a global prefix. - If you see an address starting with
2or3, the device has a global address and the problem is further away.
3. Is IPv6 enabled on the router?
Many routers ship with IPv6 switched off, or support only some modes.
- Look for an IPv6 setting under WAN or internet. Common modes are DHCPv6-PD (prefix delegation, the most common for fibre connections with IPv6), SLAAC or 6rd.
- Make sure the router advertises the prefix on the local network (Router Advertisements, sometimes called “LAN IPv6” or “RA”).
- Restart the router after the change.
4. Does your subscription include it?
If the router gets no IPv6 prefix on its WAN side, your provider probably doesn’t offer IPv6 on your subscription, or it has to be activated. Ask support specifically: “Do you offer native IPv6 with prefix delegation on my subscription, and what prefix size do I get?” The answer is usually /56 or /64.
5. IPv6 is there, but sites load slowly
If the browser tries IPv6 first and the path is broken, it waits before falling back to IPv4 (Happy Eyeballs). Typical causes:
- The firewall blocks ICMPv6. IPv6 needs ICMPv6 to work (among other things, to find the right packet size) — don’t block it entirely.
- MTU problems in tunnels or PPPoE: large packets disappear, small ones get through. Pages start loading and then stall.
- A stale DNS cache, or a resolver that returns AAAA answers when there is no IPv6 path.
Toggle Wi-Fi or try another device on the same network to see whether the fault is in one device or in the router.
6. Check a specific site
If only one site misbehaves, look up its AAAA record with the DNS lookup and check that the address actually answers. It may be the site, not your connection, that has broken IPv6.
Do I need IPv6?
Not to browse — everything works over IPv4. But IPv6 gives your devices their own public addresses without CGNAT, which makes reaching things at home from outside easier and removes a translation step at your provider.