Fix IPv6 No Internet Access on Windows 10/11

Symptoms

• Network icon shows 'No Internet Access' or limited connectivity.
• IPv6 connectivity displays 'No Internet Access' in Network and Sharing Center.
• Websites load slowly or fail to load, especially IPv6-only sites.
• Running ipconfig /all shows an IPv6 address starting with 'fe80::' (link-local) but no global unicast address.
• Ping to IPv6 addresses (e.g., ping -6 google.com) fails.

Root Causes

• DHCPv6 failure: Windows fails to obtain a valid IPv6 address from the router or ISP.
• Corrupted network adapter settings: Misconfigured IPv6 parameters or driver issues.
• Firewall or security software: Blocking DHCPv6 or ICMPv6 traffic.
• Router issues: IPv6 not enabled or misconfigured on the router.
• Windows registry corruption: Invalid entries in IPv6-related registry keys.
• IPv6 tunneling protocols: Issues with Teredo, ISATAP, or 6to4 adapters.

Step-by-Step Fix

Step 1: Run Network Troubleshooter

1. Open Settings > Network & Internet > Status.
2. Click Network troubleshooter and follow prompts.
3. If no fix, proceed to Step 2.

Step 2: Reset Network Adapter

1. Open Control Panel > Network and Sharing Center > Change adapter settings.
2. Right-click your active adapter (e.g., Ethernet or Wi-Fi) and select Disable.
3. Wait 10 seconds, then right-click and Enable.
4. Check if IPv6 obtains a global address.

Step 3: Release and Renew IPv6 via Command Prompt

1. Press Win + R, type cmd, right-click and Run as administrator.
2. Run the following commands one by one:

   ipconfig /release6
   ipconfig /renew6

3. Then run ipconfig /all to verify a valid IPv6 address (not starting with fe80).

Step 4: Reset Winsock and IPv4/IPv6 Stack

1. In the same admin command prompt, run:

   netsh winsock reset
   netsh int ipv6 reset
   netsh int ipv4 reset

2. Restart your computer.

Step 5: Disable and Re-enable IPv6

1. Open Control Panel > Network and Sharing Center > Change adapter settings.
2. Right-click your adapter > Properties.
3. Uncheck Internet Protocol Version 6 (TCP/IPv6).
4. Click OK and restart your PC.
5. Re-enable IPv6 by checking the box again and restart.

Step 6: Reset IPv6 Registry Settings

1. Press Win + R, type regedit, press Enter.
2. Navigate to:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters

3. Delete the DisabledComponents value if it exists (or set it to 0).
4. Restart your PC.

Step 7: Update Network Drivers

1. Open Device Manager (right-click Start > Device Manager).
2. Expand Network adapters, right-click your adapter, select Update driver.
3. Choose Search automatically for drivers.
4. If no update, visit your manufacturer's website for the latest driver.

Step 8: Check Router IPv6 Settings

1. Log into your router (usually 192.168.1.1 or 192.168.0.1).
2. Look for IPv6 settings (often under Advanced or WAN).
3. Ensure IPv6 is Enabled and set to DHCPv6 or SLAAC as per your ISP.
4. Save and reboot the router.

Alternative Fixes

• Disable IPv6 tunneling: In admin command prompt, run netsh int teredo set state disabled, netsh int isatap set state disabled, netsh int 6to4 set state disabled. Restart.
• Use a static IPv6 address: If your ISP provides one, manually enter it in adapter properties.
• Disable IPv6 privacy extensions: Run netsh int ipv6 set global randomizeidentifiers=disabled.
• System Restore: Roll back to a point when IPv6 worked.

Prevention

• Keep Windows and network drivers updated.
• Avoid manually disabling IPv6 unless necessary.
• Regularly reboot your router and modem.
• Use a reliable firewall that doesn't block DHCPv6.
• Monitor router firmware updates for IPv6 improvements.
• If using VPN, ensure it supports IPv6 or disable IPv6 on the VPN adapter.

After applying these steps, your IPv6 connectivity should be restored. If the issue persists, contact your ISP to verify IPv6 support on their end.