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What Does It Mean If IPv6 Is Enabled But Not Working?

Quick Answer

When IPv6 is "enabled but not working," it means your device has IPv6 turned on and may even have an IPv6 address assigned, but it cannot successfully communicate with IPv6-enabled websites and services. This is known as broken IPv6 or non-functional IPv6, and it's actually worse than having no IPv6 at all because it causes connection delays and timeouts.

Understanding Enabled vs. Functional IPv6

Enabled IPv6

Functional IPv6

The critical difference: enabled means it's configured; functional means it actually works end-to-end.

Why Broken IPv6 Is Problematic

When IPv6 is enabled but broken, your internet experience suffers in several ways:

  1. Connection Delays: Modern browsers prefer IPv6 over IPv4. When IPv6 is available but broken, the browser attempts IPv6 first, waits several seconds for it to timeout, then falls back to IPv4. This adds 3-10 seconds to every website load.

  2. Some Sites Won't Load: Certain applications and websites may fail completely if IPv6 times out rather than failing fast.

  3. Intermittent Issues: You may experience inconsistent connectivity where some sites work fine (IPv4-only) while others are slow or fail (dual-stack sites that offer both protocols).

  4. Poor User Experience: Video streaming, gaming, and real-time applications suffer the most from IPv6 timeout delays.

Common Causes of Broken IPv6

1. ISP-Level Problems

Incomplete IPv6 Deployment Many ISPs have partially deployed IPv6 but haven't fully tested or activated it for all customers. You might receive an IPv6 address but lack proper routing to the broader IPv6 internet.

Symptoms:

Solution:

2. Router and Gateway Issues

Outdated Firmware Many home routers received IPv6 support through firmware updates, but older firmware versions may have bugs or incomplete implementations.

Configuration Problems

Symptoms:

Solutions:

3. Firewall Blocking

ICMPv6 Filtering IPv6 relies heavily on ICMPv6 for critical functions like neighbor discovery, router discovery, and Path MTU Discovery. Unlike IPv4 where ICMP is often safely blocked, blocking ICMPv6 breaks IPv6 functionality.

Overly Restrictive Rules

Symptoms:

Solutions:

4. MTU and Fragmentation Issues

Path MTU Discovery Failures When firewalls block ICMPv6 "Packet Too Big" messages (type 2), Path MTU Discovery fails. This causes large packets to be dropped silently.

Symptoms:

Solutions:

5. DNS Configuration Problems

IPv6-Capable DNS Servers Missing Your DNS server might not support AAAA record queries or may have IPv6 connectivity issues itself.

Symptoms:

Solutions:

6. Operating System Issues

Outdated Network Drivers Network adapter drivers may have IPv6 bugs or incomplete support in older versions.

Corrupted Network Stack Windows registry corruption or configuration errors can break IPv6 specifically.

Symptoms:

Solutions:

Diagnosing Your Specific Problem

Step 1: Run a Comprehensive Test

Visit test-ipv6.run for a complete diagnosis. This tool performs six parallel tests:

The test will specifically identify if you have broken IPv6 (enabled but timing out), which scores 0/10 and appears in red.

Step 2: Check Your IPv6 Address Type

Look at your assigned IPv6 address:

Step 3: Test Basic Connectivity

# Ping an IPv6-only server
ping6 ipv6.google.com

# Trace the route
traceroute6 test-ipv6.run

# Check your routing table
ip -6 route (Linux)
netsh interface ipv6 show route (Windows)

Step 4: Test DNS Resolution

# Query AAAA records
nslookup -type=AAAA test-ipv6.run

# Verify your DNS server supports IPv6
dig AAAA test-ipv6.run @2001:4860:4860::8888

Step 5: Check Firewall Rules

# Linux: Check ip6tables rules
sudo ip6tables -L -v

# Windows: Check firewall status
netsh advfirewall show allprofiles

Solutions for Common Scenarios

Scenario 1: ISP Doesn't Fully Support IPv6

Best Solution: Contact ISP and request proper IPv6 support or disable IPv6 entirely to avoid timeouts.

Temporary Workaround: Disable IPv6 on your device to prevent connection delays.

Scenario 2: Router Configuration Issues

Solution:

  1. Log into router admin panel
  2. Check IPv6 settings under WAN/Internet configuration
  3. Verify correct mode (usually DHCPv6-PD or SLAAC)
  4. Ensure Router Advertisements are enabled
  5. Save settings and reboot router

Scenario 3: Firewall Blocking

Solution:

  1. Create specific allow rules for ICMPv6
  2. Allow IPv6 traffic on ports 80, 443 for basic web browsing
  3. Test with firewall temporarily disabled to confirm
  4. Re-enable with proper rules

Scenario 4: Windows "No Network Access"

Solution:

# Run as Administrator
netsh winsock reset
netsh int ipv6 reset
ipconfig /flushdns
# Restart computer

Solution:

  1. Check router's IPv6 WAN status (should have global address)
  2. Verify Router Advertisements are enabled
  3. Restart DHCP client service
  4. Check for MAC address filtering or client isolation

When to Disable IPv6

You should consider disabling IPv6 if:

  1. Your ISP doesn't support it and you're getting timeouts
  2. Your router is too old for proper IPv6 support
  3. Troubleshooting confirms IPv6 is causing application failures
  4. Corporate policy requires IPv4-only
  5. You need immediate stable connectivity and can't fix IPv6 issues

How to Disable IPv6:

Initial Diagnosis

  1. Visit test-ipv6.run for comprehensive testing
  2. Review your score and specific test results
  3. Note any "broken IPv6" warnings (score 0/10, red indicator)

After Making Changes

  1. Retest at test-ipv6.run
  2. Verify dual-stack test passes (most critical)
  3. Check that IPv6 latency is reasonable (<100ms for most sites)
  4. Confirm no timeout warnings

Ongoing Monitoring

Conclusion

IPv6 being "enabled but not working" is a common problem that creates a worse user experience than having no IPv6 at all. The key is identifying whether the issue is at your ISP, router, firewall, or OS level, then applying the appropriate fix. Use comprehensive testing tools like test-ipv6.run to diagnose the specific problem, and don't hesitate to contact your ISP if the issue is on their end.

Remember: Broken IPv6 scores 0/10 because it actively degrades your internet experience through timeouts and delays. It's better to have working IPv4-only than broken dual-stack.

For comprehensive IPv6 connectivity testing and diagnosis, visit test-ipv6.run