IPv4 vs IPv6: What’s Different, Why It Matters, and Privacy Impacts

• 9 min read

IPv4 and IPv6 are two versions of the Internet Protocol. In practice, the biggest surprise for most people is: you may have both at the same time. That’s normal—and it matters for privacy because IPv6 can sometimes bypass a VPN if it’s not configured correctly.

Check what you have

Your connection may expose an IPv4, an IPv6, or both. Start here:

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Check My IP

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VPN Detection

What is IPv4?

IPv4 is the older protocol. IPv4 addresses look like 203.0.113.42 (four numbers separated by dots). There are only about 4.3 billion possible IPv4 addresses, and the internet ran out long ago—this is why we see NAT and CGNAT so often.

What is IPv6?

IPv6 is the newer protocol designed to solve address exhaustion. IPv6 addresses look like 2001:db8:85a3::8a2e:370:7334 (hexadecimal with colons). IPv6 allows an enormous address space, enabling more direct addressing and reducing the need for NAT.

Why you may have both (dual-stack)

Most modern networks run dual-stack: devices can use IPv4 and IPv6 depending on what the destination supports. Many websites and CDNs prefer IPv6 when it’s available because it can be faster and simpler routing-wise.

Privacy: what changes with IPv6?

1) IPv6 can “leak” if your VPN isn’t handling it

Some VPNs only tunnel IPv4 by default. If your device still has working IPv6, some traffic can leave outside the tunnel, exposing your real IPv6 address.

Fix: Use a VPN that supports IPv6 properly, or disable IPv6 on your device/router if your VPN provider recommends it. Always verify after connecting:

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Verify VPN

2) Geolocation still works (approximate)

IPv6 geolocation is still approximate and can be wrong for many of the same reasons as IPv4 (mobile routing, shared infrastructure, database lag). If your location looks off, read:

3) Some networks use privacy extensions (good)

Devices can rotate the interface portion of IPv6 addresses (privacy extensions) to reduce tracking on local networks. This does not replace the need for a VPN, but it reduces one class of passive tracking.

Practical differences you’ll notice

  • Streaming/gaming: usually no difference unless a service blocks VPNs or there’s an IPv6 leak.
  • Home networking: IPv6 can reduce NAT issues, but many setups still rely heavily on IPv4.
  • Troubleshooting: you may need to test both stacks when diagnosing connectivity.

What to do if you suspect an IPv6 leak

  1. Connect to your VPN.
  2. Run VPN Detection and confirm the IPs shown match the VPN.
  3. If you still see your ISP or real location, check VPN settings for IPv6 support or disable IPv6 temporarily.

Next steps