IPv6 — dual-stack, what 'inactive' means, and the one thing to watch

Native IPv6 is a bonus, not a requirement. Half-working IPv6 is worse than none — that's the case to recognise.

What the line means. *Native IPv6 active* means your ISP hands out a public IPv6 prefix and this machine has a global address (starts 2xxx: or 3xxx:). *IPv4 only* means it doesn't — which is still perfectly normal in 2026 on many networks.

Addresses you'll see. fe80::… is *link-local*: every interface has one, it never leaves the LAN, and it does not mean you have IPv6 internet. fd..: is a private (ULA) range — Tailscale uses one.

The trap: half-working IPv6

Operating systems prefer IPv6 when a name has both kinds of address. If your IPv6 is configured but broken (a router that advertises a prefix it can't route, a firewall dropping it), every dual-stack site starts with a failed IPv6 attempt, then falls back — so pages feel slow to *start* and then load fine. If n ping . shows IPv6 active but n check to a big site is oddly slow, test with IPv6 disabled on the adapter; if it gets snappy, fix or turn off IPv6 at the router.

Security note

There is no NAT on IPv6. Every device with a global address is directly addressable from the internet; your router's IPv6 firewall is the only thing in the way. Check it's on (most are by default). n firewall . covers this machine's side.