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How to fix DNS issues after enabling IPv6

This guide will help you restore reliable internet connectivity by troubleshooting DNS problems that appear after you turn on IPv6. You will learn how to test your connection, adjust device and router settings, and choose the right DNS servers for a stable dual-stack network.

We'll walk through simple diagnostics and safe configuration changes to get your websites loading again.

Note: Steps may vary by device and router model. This guide focuses on safe, general methods.

Quick Answer

If websites won't load after enabling IPv6, your device is likely trying to use IPv6 for DNS lookups and failing. Here’s the fastest fix:

Restart your computer and router.
On your device, change DNS settings to use a public server like Google (8.8.8.8, 8.8.4.4) or Cloudflare (1.1.1.1).
On your router, ensure IPv6 DNS is configured and not left blank.
Flush your device's DNS cache.
Temporarily disable any VPN or security software to test.

If this doesn’t work, follow the diagnostic flow below to pinpoint the exact cause.

What you need

Before you start

Access to your router's admin page (IP, username, password).
A computer connected to your network (Wi-Fi or Ethernet).
Basic knowledge of how to change network adapter settings.
Your ISP details (they may provide specific IPv6 settings).
A note of your current DNS settings (if any).

Good to know

IPv6 is a newer internet addressing system that runs alongside IPv4.
DNS translates domain names (like example.com) to IP addresses.
Your device may prefer IPv6 DNS servers if available, which can fail.
Public DNS services often have more reliable IPv6 support.
Some older routers or ISP modems handle IPv6 DNS poorly.

Diagnose the issue in 2 minutes

Is it only one device or all devices?
- One device: Problem is likely on that device's settings.
- All devices: Problem is likely with your router or ISP.
Can you ping an IPv6 address?
ping 2001:4860:4860::8888

If this fails but a ping to 8.8.8.8 works, IPv6 connectivity is broken.
Can you resolve a domain name using only IPv6?
nslookup google.com 2001:4860:4860::8888

If this fails, your specified IPv6 DNS server is not responding.
Is a VPN or firewall active? Temporarily disable it. If the problem fixes, the software is blocking IPv6.
Quick check: Try browsing to a website by its IP address (e.g., http://142.250.185.78). If it works, your connection is fine but DNS is broken.

Step-by-step guide

Step 1 — Restart everything

A simple restart can clear temporary glitches in DNS resolution.

Restart your computer or device having issues.
Unplug your router and modem from power for 30 seconds, then plug them back in.
Wait for all lights to stabilize.

What you should see: A fresh network connection. Test a website.

Step 2 — Check router IPv6 DNS settings

Your router must have valid DNS server addresses for IPv6.

Log into your router's admin page.
Navigate to IPv6 settings (often under "Internet" or "Advanced").
Find the DNS server fields. If they are blank or set to "Obtain automatically," try manual ones.
Enter reliable public IPv6 DNS addresses (e.g., Cloudflare: 2606:4700:4700::1111, 2606:4700:4700::1001).
Save settings and reboot the router.

What you should see: IPv6 DNS fields populated with valid addresses.

Step 3 — Change DNS on your device

Overriding DNS at the device level can bypass a faulty router configuration.

Go to your device's network settings.
Find the properties for your active connection (Wi-Fi or Ethernet).
Locate IPv4 and IPv6 DNS settings.
Change both to "Use the following DNS server addresses."
For IPv4: Use 1.1.1.1 and 8.8.8.8.
For IPv6: Use 2606:4700:4700::1111 and 2001:4860:4860::8888.

Windows: Control Panel > Network and Sharing Center > Change adapter settings.

macOS: System Preferences > Network > Advanced > DNS.

Linux: Edit connection via Settings or /etc/resolv.conf (methods vary).

What you should see: Immediate ability to browse after applying settings.

Step 4 — Flush the DNS cache

Clearing old, cached DNS records forces your system to look up fresh ones.

Windows: Open Command Prompt as Administrator. Run ipconfig /flushdns.

macOS: Open Terminal. Run sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder.

Linux: Depends on service. For systemd-resolved: sudo systemctl restart systemd-resolved.

What you should see: A confirmation message that the cache was cleared.

Step 5 — Temporarily disable IPv6

If problems persist, test if disabling IPv6 restores normal function. This confirms IPv6 is the root cause.

In your device's network adapter properties, find the TCP/IPv6 setting.
Uncheck the box for "Internet Protocol Version 6 (TCP/IPv6)".
Apply changes and reconnect.

What you should see: Internet works on IPv4 only. If it does, your IPv6 setup is faulty.

Step 6 — Check for firmware updates

Router manufacturers often fix IPv6 bugs in firmware updates.

In your router admin, find the "Firmware Update" or "Administration" section.
Check for updates. If available, follow instructions to install.
After updating, reconfigure your IPv6 and DNS settings.

What you should see: A newer firmware version and potentially resolved issues.

Common fixes by symptom

Connected but no internet

Likely causes:

Router's IPv6 gateway or DNS is misconfigured.
ISP not properly delegating IPv6 prefixes.

Safe fixes:

Set static IPv6 DNS on router (Step 2).
Contact ISP to verify they support IPv6 on your plan.

When to stop and escalate: If ISP confirms IPv6 is not supported or stable, keep it disabled.

Some websites don't open (others work)

Likely causes:

Those specific sites have broken IPv6 records (DNS AAAA records).
Your DNS server is returning invalid IPv6 addresses.

Safe fixes:

Switch to a different public DNS provider (like Cloudflare or Quad9).
Flush DNS cache (Step 4).

When to stop and escalate: If only one or two major sites fail, it's likely their problem; wait it out.

Extremely slow page loading

Likely causes:

DNS lookup is timing out because the IPv6 DNS server is unreachable.
Device is waiting for an IPv6 response before falling back to IPv4.

Safe fixes:

Use a fast, reliable DNS provider for both IPv4 and IPv6.
Lower the DNS timeout on the router if possible (advanced).

When to stop and escalate: If speed tests are fine but browsing is slow, the issue is DNS—stick with your fix.

One specific device can't connect

Likely causes:

Outdated network drivers or OS on that device.
Device has a manual, incorrect IPv6 configuration.

Safe fixes:

Update the device's OS and network drivers.
Set the device's network connection to obtain IPv6 settings automatically.

When to stop and escalate: If the device is very old and doesn't support IPv6 well, disable IPv6 on it.

Quick reference

Table A: What the metric means

Metric	What it means for DNS/IPv6
Latency	Time for a DNS query to get a reply. High latency means slow website name resolution.
Packet Loss	DNS requests or replies are being dropped. Causes timeouts and "server not found" errors.
Throughput	Not usually a DNS factor. If DNS is fine but speeds are low, check ISP or local network.
Signal Strength (Wi-Fi)	Weak signal can cause intermittent DNS failures, especially on IPv6 which may have larger packets.

Table B: Safe baseline settings

Setting	Recommended Baseline
DNS (IPv4)	1.1.1.1 (Cloudflare) or 8.8.8.8 (Google) as primary.
DNS (IPv6)	2606:4700:4700::1111 (Cloudflare) or 2001:4860:4860::8888 (Google).
Router Admin	Change default login. Use WPA2/WPA3 security.
IPv6 Mode	"Native" or "DHCPv6" if supported by ISP. Avoid "6to4" or "Teredo" if unstable.
Updates	Check for router firmware updates every 6 months.

Mind map summary

DNS Issues after Enabling IPv6
|
├── Is it ONE device or ALL devices?
│   ├── One Device → Focus on its settings.
│   │   ├── Update OS/Drivers.
│   │   ├── Change DNS to manual (IPv4 & IPv6).
│   │   └── Flush DNS cache.
│   └── All Devices → Focus on Router/ISP.
│       ├── Check Router IPv6 DNS config.
│       ├── Update Router Firmware.
│       └── Contact ISP for IPv6 support.
|
├── Quick Tests
│   ├── Ping IPv6 address → Fails? IPv6 connectivity broken.
│   ├── nslookup with IPv6 DNS → Fails? DNS server broken.
│   └── Browse by IP → Works? DNS is the problem.
|
└── Main Remedies
    ├── Set reliable public DNS (Cloudflare, Google).
    ├── Ensure router passes DNS correctly.
    ├── Restart devices & router.
    └── Last resort: Disable IPv6 on problem device.

Troubleshooting checklist

Device

Restarted the device?
DNS set to manual with valid IPv4/IPv6 addresses?
DNS cache flushed?
IPv6 temporarily disabled as a test?
OS and drivers updated?

Router

Router restarted (power cycle)?
IPv6 DNS fields populated in admin?
Firmware updated?
IPv6 connection type correct for ISP?

ISP & External

ISP supports IPv6 on your plan?
VPN/security software turned off for testing?
Tested with different public DNS servers?
Problem occurs on both Wi-Fi and Ethernet?

When to escalate

Contacting your ISP

Triggers:

No devices get IPv6 addresses even with router set to "automatic".
ISP-provided modem/router combo fails with IPv6 enabled.
You've verified correct settings but IPv6 connectivity is inconsistent.

What to collect before calling:

Router make/model and firmware version.
IPv6 address and prefix from router WAN status.
Results of ping tests to IPv6 addresses.
Exact error messages or symptoms.

Replacing your router

Consider if:

Router firmware is years old and no updates are available.
IPv6 features are missing or constantly buggy across multiple devices.
The router frequently crashes or overheats when IPv6 is enabled.

Asking IT support

For workplace or advanced networks:

You suspect firewall rules are blocking IPv6 DNS (port 53 over IPv6).
You need to configure IPv6-specific DHCP options.
You are dealing with a complex dual-stack corporate network.

FAQ

Should I just disable IPv6 if it's causing problems?

Disabling IPv6 is a valid temporary or permanent workaround, especially on older networks. However, the internet is gradually moving toward IPv6. If you can fix the DNS issues, keeping it enabled is better for long-term compatibility and performance with modern websites and services.

How do I know if my ISP supports IPv6?

Visit a test website like "test-ipv6.com" from a device on your network with IPv6 enabled on your router. If you get a high score (9/10 or 10/10), your ISP supports it. Otherwise, check your ISP's support pages or contact them directly.

What's the difference between IPv4 DNS and IPv6 DNS?

The function is identical: translating domain names to IP addresses. The difference is the protocol used for the query and the format of the addresses returned. IPv6 DNS servers are queried over IPv6 and return longer, hexadecimal addresses (like 2606:4700:4700::1111).

Can using public DNS like Cloudflare slow down my internet?

Usually the opposite. Public DNS servers are often faster and more reliable than default ISP DNS. In rare cases, a geographically closer ISP DNS might be marginally faster, but the difference for typical browsing is negligible. The reliability benefit usually outweighs any tiny latency increase.

Why did DNS work fine before I enabled IPv6?

Your devices were using only IPv4 for DNS queries and connections. When IPv6 is enabled, devices often prefer to use IPv6 for DNS if available. If the configured IPv6 DNS server is unreachable or misconfigured, those lookups fail, causing website loading issues.

Is IPv6 less secure than IPv4?

No, IPv6 was designed with modern security in mind and includes IPsec as a standard feature. However, any new protocol can have implementation bugs. The security risk usually comes from misconfiguration, not the protocol itself. Using a firewall and keeping devices updated is key for both.

My router has an "IPv6 Passthrough" mode. Should I use it?

This mode is typically used when you have a separate modem that handles the IPv6 connection. It allows the modem's IPv6 settings to pass directly to your devices. Use this if your ISP's modem is already providing full IPv6 and your router is acting as a simple access point.

Will changing my DNS affect my VPN?

It can. Most VPNs force all your traffic, including DNS, through their secure tunnel using their own DNS servers. If you change your device's DNS manually, the VPN may override it. If you're having DNS issues with a VPN active, check the VPN's settings or contact their support.

Sources and references

Microsoft Windows Networking Documentation (IPv6 configuration and troubleshooting)
Apple macOS Support Articles (Network advanced settings and DNS management)
Linux man pages for systemd-resolved, NetworkManager, and ip commands
Router vendor administration guides (General IPv6 setup concepts)
Internet Engineering Task Force (IETF) RFCs on IPv6 and DNS operation
Wi-Fi Alliance and IEEE 802.11 standards overview
General networking diagnostics principles (ping, traceroute, nslookup)
Cybersecurity and Infrastructure Security Agency (CISA) guidelines on home network security

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How to fix DNS issues after enabling IPv6

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