IPv4 vs IPv6: What's the Difference and Does It Matter?

Published July 26, 2026 · 7 min read

Open your iPhone's network settings and you will probably see two IP addresses sitting side by side: something short like 192.168.1.42, and something long like 2600:1700:abcd:1234::5. The first is IPv4. The second is IPv6. Most people have never had to think about the difference, because their devices have quietly been speaking both for years.

Here is what the two protocols actually are, why IPv6 exists at all, and whether it is worth doing anything about on your own network.

What IPv4 and IPv6 Actually Are

Every device on the internet needs an address, the same way every house needs one for mail to arrive. IPv4 (Internet Protocol version 4) is the addressing scheme that has run the internet since the 1980s. It writes addresses as four numbers separated by dots, like 192.168.1.1, and it has room for about 4.3 billion unique addresses.

That sounded like plenty in 1981. It is not plenty for a planet with billions of phones, laptops, routers, smart TVs, and light bulbs all wanting their own address. IPv6 (Internet Protocol version 6) is the replacement, designed specifically to fix that shortage. It writes addresses as eight groups of hexadecimal digits separated by colons, like 2600:1700:abcd:1234:0000:0000:0000:0005, usually shortened to 2600:1700:abcd:1234::5. The address space is not just bigger, it is 340 undecillion addresses, roughly enough for every grain of sand on Earth to have billions of its own.

Why the Internet Ran Out of IPv4 Addresses

The regional registries that hand out IPv4 blocks started running dry in the early 2010s, and most have been effectively exhausted for years. The internet did not stop working, because two workarounds bought enormous amounts of time: NAT (Network Address Translation), and reusing private address ranges.

NAT is why your whole household shares one public IPv4 address. Your router hands your phone, laptop, and smart speaker private addresses like 192.168.1.x, then translates all their traffic through a single public IPv4 address on its way out. It works well, but it means the open internet only sees your router, not each device, which is also why port forwarding exists: it tells the router which internal device should receive traffic aimed at a specific port.

NAT solved the shortage for individual homes, but it added complexity everywhere, especially for anything that needs a device to be directly reachable, like gaming, video calls, or self-hosting. IPv6 was designed to remove the need for NAT entirely by giving every device its own address again.

What Actually Changes with IPv6

For most people, remarkably little changes day to day, which is by design. A handful of things are genuinely different under the hood:

• No NAT needed. With enough addresses for everyone, each device can get its own public IPv6 address directly, though most home routers still firewall unsolicited inbound connections by default, so this is not the security downgrade it sounds like.
• Simpler routing. IPv6 was designed with a leaner header and none of the fragmentation-in-transit baggage IPv4 carries, which can shave a small amount of overhead off every packet.
• Built-in address autoconfiguration. IPv6 devices can generate their own address and find the network's router without DHCP, using a process called SLAAC.
• Privacy extensions. To stop a fixed IPv6 address from becoming a long-term tracking identifier, modern devices, including iPhones, rotate a temporary IPv6 address for outgoing connections. This is a different mechanism from the per-network private WiFi (MAC) address feature, but they serve the same privacy goal.

Is IPv6 Faster? Is It Slower?

Neither, in most real-world cases. The protocol difference itself is not the bottleneck for typical home browsing and streaming. What actually matters is how well a specific network path supports IPv6. Where IPv6 tends to win is on networks and CDNs that have invested in native IPv6 peering, since traffic can travel a more direct path without translation. Where it can lose is on a poorly configured IPv6 rollout, where a device tries IPv6 first, times out, then falls back to IPv4, adding a real, noticeable delay. That fallback behavior, not the protocol itself, is where most "IPv6 made my internet slow" complaints come from.

If a site or game feels slower right after your ISP announces an IPv6 rollout, that fallback delay is the first thing worth checking with a traceroute or ping test against both address types.

Dual Stack: Why You Are Probably Using Both Right Now

Almost every modern network runs dual stack, meaning devices are assigned both an IPv4 and an IPv6 address simultaneously and pick whichever works best for each connection. That is exactly the two addresses you saw in your iPhone's WiFi settings at the top of this article. Dual stack is the reason the transition from IPv4 has been so invisible: nothing had to break, because both protocols simply ran side by side while the internet gradually shifted more traffic to IPv6 over time.

How to Check Which One You Are Using

1. Check your device's local address. On iPhone, open Settings › WiFi › tap the (i) next to your network, or check PingKit's Network Info tool, which lists both your IPv4 and IPv6 addresses side by side.
2. Check your public address. Your public IP address is what the outside internet sees. If your ISP supports IPv6, you will have a public IPv6 address in addition to your shared IPv4 one.
3. Test connectivity to both. Run a ping or traceroute against an IPv6-only and an IPv4-only target to see whether each path is healthy and to compare latency.

Do You Need to Do Anything About It?

For almost everyone, no. IPv6 is designed to work transparently alongside IPv4, and disabling it rarely helps; it occasionally causes more problems than it solves, since some services now expect it. The cases where it is worth paying attention are narrow: if you are troubleshooting a specific game or app that behaves oddly, if you are setting up port forwarding and need to know which protocol a service actually listens on, or if you are simply curious what your router and ISP are doing under the hood. Outside of that, the right amount of effort to spend on IPv4 vs IPv6 is close to zero, which is precisely what the people who designed the transition were hoping for.

The Bottom Line

IPv4 is the original addressing scheme the internet was built on, and it ran out of room decades before anyone expected. IPv6 fixes the shortage with a vastly larger address space and removes the need for NAT, but for day-to-day use the difference is invisible, because dual stack quietly runs both at once and picks whichever works best. The only time it is worth checking which one you are on is when something specific is broken, like a game connection or a port-forwarding rule, and even then a quick look at your Network Info screen usually answers the question in seconds.

Frequently Asked Questions

What is the main difference between IPv4 and IPv6?

IPv4 uses a 32-bit address format with room for about 4.3 billion addresses, written as four numbers like 192.168.1.1. IPv6 uses a 128-bit format with a vastly larger address space, written as eight hex groups like 2600:1700:abcd:1234::5, and does not require NAT for every device to get its own address.

Is IPv6 faster than IPv4?

Not inherently. Speed depends on how well a specific network path supports IPv6. A well-peered IPv6 route can be marginally faster; a poorly configured one can add a fallback delay while a device tries IPv6 first and times out before switching to IPv4.

Do I need to enable IPv6 myself?

Almost never. Most modern networks run dual stack automatically, assigning both IPv4 and IPv6 addresses without any setup, and your devices pick the best one per connection on their own.

Why does my iPhone show two different IP addresses?

Because it is running dual stack: one shorter IPv4 address and one longer IPv6 address, assigned at the same time. Your device chooses which protocol to use for each individual connection.

Does IPv6 remove the need for port forwarding?

It removes the need for NAT to share one address among many devices, but most home routers still firewall unsolicited inbound IPv6 connections by default, so you will typically still need an explicit rule to let a specific service through, just as with IPv4.