Dual-Stack Connectivity Checker

Check if your connection supports both IPv4 and IPv6. Test dual-stack connectivity by fetching IPv4 and IPv6 API endpoints.

What Is Dual-Stack?

A dual-stack network runs both IPv4 and IPv6 simultaneously. This is the primary transition strategy recommended for moving from IPv4 to IPv6 — rather than switching overnight, both protocols coexist. Your devices get both an IPv4 address (like 192.168.1.x) and an IPv6 address. Applications prefer IPv6 when available (Happy Eyeballs algorithm) and fall back to IPv4 when needed.

Dual-Stack Status Meanings

Status	Meaning	Action
Full Dual-Stack	Both IPv4 and IPv6 working	Optimal — no action needed
IPv4 Only	No IPv6 connectivity	Enable IPv6 on router or contact ISP
IPv6 Only	No IPv4 connectivity	Rare; may need NAT64 for IPv4-only sites
Neither	No internet connectivity	Check network connection

Pro Tip: If you only have IPv4, check your router settings at 192.168.1.1 — IPv6 may just need to be enabled. Most modern ISPs support IPv6 but some routers ship with it disabled by default. Look for an IPv6 or DHCPv6 option in the WAN/Internet settings. After enabling, use this checker to verify both protocols are working.

Note: This checker tests your connection from your browser. Results may differ from server-side tests because your ISP, router, and operating system all affect IPv6 availability. If your ISP supports IPv6 but this test shows IPv4 only, check: (1) IPv6 is enabled on your router, (2) your device's IPv6 is enabled, (3) no firewall is blocking IPv6. Use our What Is My IP tool for detailed address information.

Enabling IPv6 on Your Network

# Check IPv6 on Windows
ipconfig /all | findstr "IPv6"

# Check IPv6 on Linux
ip -6 addr show

# Check IPv6 on macOS
ifconfig | grep inet6

# Test IPv6 connectivity
ping6 google.com        # Linux/macOS
ping -6 google.com      # Windows

For router configuration, see our guides for logging into 192.168.1.1 or 10.0.0.1. Most routers have IPv6 settings under the WAN or Internet section.

Key Takeaways

Dual-stack means running IPv4 and IPv6 simultaneously — the recommended transition approach.
Most modern ISPs support IPv6, but it may need to be enabled on your router.
Applications prefer IPv6 when available (Happy Eyeballs) and fall back to IPv4 automatically.
Use this checker to verify both protocols are working, and What Is My IP for address details.
If IPv6 is missing, check router settings, device configuration, and ISP support.

Video Guide

Related Tools

Frequently Asked Questions

How do I check if I have IPv6?

Click the Check button above or visit What Is My IP. If you see an IPv6 address alongside your IPv4, you have dual-stack connectivity.

Why is IPv6 important?

IPv4 addresses are exhausted. IPv6 provides virtually unlimited addresses, eliminates NAT, and improves end-to-end connectivity for modern applications.

Does dual-stack slow down my internet?

No. Dual-stack adds negligible overhead. The Happy Eyeballs algorithm ensures the fastest protocol is used for each connection.

How do I enable IPv6?

Log into your router, find the IPv6/WAN settings, and enable it. Most ISPs assign IPv6 automatically via DHCPv6 or SLAAC.

What if my ISP does not support IPv6?

You can use tunnel brokers like Hurricane Electric (tunnelbroker.net) to get IPv6 over your IPv4 connection. Or use our 6to4 Tunnel Calculator.

About Tommy N.

Tommy is the founder of RouterHax and a network engineer with 10+ years of experience in home and enterprise networking. He specializes in router configuration, WiFi optimization, and network security. When not writing guides, he's testing the latest mesh WiFi systems and helping readers troubleshoot their home networks.