IPv4 vs IPv6

The short story: IPv4 is running out of addresses, so IPv6 was created with many more. We didn’t flip a big switch. Both versions run side‑by‑side while the world upgrades.

TL;DR: IPv4 = the old, crowded neighborhood. IPv6 = the new area with lots of empty houses.

The quick idea

IPv4 uses 32 bits (~4.3 billion addresses). That felt huge in the 1980s, but now every phone, TV, car, and doorbell wants one. To stretch it, we use NAT (many devices hide behind one public number).
IPv6 uses 128 bits (a huge number of addresses). Every device can have a public address. This makes routing and connecting simpler.
Not a speed button: IPv6 isn’t automatically faster. Your device tries both (this is called Happy Eyeballs) and uses the one that answers first.

Why both still exist

There’s too much gear on IPv4 to change overnight. So we use dual‑stack: try IPv6 first, use IPv4 if needed. This long overlap will last for years.

Most routers (Eero, TP‑Link, ASUS, UniFi, etc.) and many ISPs support IPv6. If you see an “Enable IPv6” toggle, turn it on. Your phone and laptop will hold both IPv4 and IPv6 and choose the better path.

If a very old site or a VPN breaks (rare), you can turn IPv6 off for that network.

Common situations

Gaming: IPv6 can remove some NAT headaches like “Strict NAT.” It won’t magically lower ping, but connections can be smoother when the game and peers support IPv6.
Smart home & remote access: With IPv6 your devices can be reachable directly, which makes “connect back home” easier. Keep your firewall closed by default and only open what you must.
Running a site or small API: Turn on dual‑stack and add an AAAA DNS record. Many mobile networks prefer IPv6 when available. The win is reachability and fewer translation steps.

Differences worth remembering

Looks: 203.0.113.7 is IPv4; 2001:db8::1 is IPv6 (the :: just means “a bunch of zeros”).
Scale: IPv6 has far more addresses and is given out in tidy blocks, which helps large‑scale routing.
NAT: IPv4 relies on NAT. IPv6 doesn’t require NAT; you still use a firewall.
Setup: Devices can self‑configure on IPv6 (SLAAC) or you can use DHCPv6.

Do you need to act?

Regular users: Mostly no. If your router/ISP support IPv6, enable it and carry on.
Site/app owners: Ship dual‑stack, add AAAA, keep inbound rules default‑deny, and test your logs.

Wrap‑up

We keep IPv4 for compatibility and add IPv6 so the internet can grow without running out of addresses. For most people, the best result is simple: things just connect.

Final takeaway: IPv4 keeps things working; IPv6 makes room for the future.