Docker failure in DNS

Technical Support
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Hi, I’m the Toradex AI Assistant.

I might make mistakes or occasionally get you wrong. Our support team will step in if needed.

Based on your detailed analysis, this appears to be a Docker networking issue specific to your WiFi environment. The fact that curl works but docker login fails suggests a Docker daemon networking problem rather than general connectivity issues.

Troubleshooting Steps

Network Configuration Analysis

Your issue shows that while basic HTTP connectivity works (curl succeeds), Docker’s networking layer is failing (1). The timeout during docker login combined with repeated DNS queries suggests Docker may be having issues with IPv6 or specific network routing (1).

IPv6 Configuration Issue

The key clue is your curl -6 command failing with “Couldn’t connect to server” while IPv4 works fine (1). Your nslookup shows both IPv4 and IPv6 addresses for registry-1.docker.io, but your network may not properly support IPv6 routing (1).

Docker Daemon Configuration

To resolve this, you can configure Docker to prefer IPv4 or disable IPv6 entirely. Modify /etc/docker/daemon.json with the following content (2):

{
  "ipv6": false,
  "ip": "0.0.0.0"
}

(2)

After making this change, restart the Docker service:

sudo systemctl restart docker

Alternative: Network-Specific DNS Configuration

If the IPv6 issue persists, you can also try configuring Docker to use specific DNS servers by adding to /etc/docker/daemon.json (2):

{
  "dns": ["8.8.8.8", "8.8.4.4"],
  "ipv6": false
}

(2)

Low-Bandwidth Connection Considerations

Since you mentioned this works on other networks, this specific WiFi network might have bandwidth or stability issues affecting Docker operations. For OTA updates with network challenges, consider configuring Aktualizr for low-bandwidth connections or implementing a pull-through cache (2).

The pull-through cache can help by creating a local registry mirror. You can set up a local cache using the registry configuration provided in the documentation (2).

Verification Steps

After implementing the Docker configuration changes:

  1. Test Docker login again
  2. Verify OTA updates work properly
  3. Monitor the network traffic to confirm IPv4-only connections

This should resolve the Docker networking issue you’re experiencing on this specific WiFi network.

Best regards, Toradex AI Assistant.

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