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Debugging DNS problems on Turris routers

Do I have DNS problem?

Yes, it is a DNS problem

Often, problems related to DNS result in improbable error messages in web browsers. For example, web browser claims that does not exist:

If your web browser reports that a website does not exist while it works while using different Internet connection (e.g. when using mobile Internet connection), follow this guide.

No, it is something else

On the other hand, it is unlikely that you have a DNS problem if the page loads but reports some other error, e.g. 503 Server Unavailable:

This guide will likely not help you in such cases.

Gather the data

Before you touch router configuration in an attempt to self-fix the problem it is necessary to gather data about the problem and send them to support. The data are necessary for detailed diagnostics and will allow us to improve software so the problem does not happen again either to you nor other users.

First of all, the data gathering process must be started before the problem manifests. This is the first step you have to do because the verbose logging is not enabled by default for performance and privacy reasons.

1. Install resolver-debug package

Package for debugging resolver isn't preinstalled by default in Turris OS. It needs to be installed manually.

 Picture 1

  1. Go to LuCI interface (or in LuCI menu System→Software)
  2. Update lists by pressing the button (you can do it in CLI with command opkg update)
  3. Write resolver-debug to textbox Download and install package and click to OK button (number one in Picture 1)

2. Enable verbose logging

 Picture 2 Verbose logs allow us to see how exactly the DNS resolver got into state where it does not function properly.

If the problem occurs only occasionally, it is better to enable verbose logging now and wait. It would be too late to enable verbose logging after the problem occurred.

  1. Go to LuCI page for custom system commands (or in LuCI menu System→Custom Commands )
  2. Click to Run button under Start resolver debugging ( number 1 in Picture 2 )

2. Attempt to visit a problematic website

After enabling verbose logging, it is necessary to time visit the site which manifests the problem from time to time. If the site still works you have to wait longer. When the site stops working continue with next step, where you will download verbose logs.

3. Download verbose logs

When the site stopped working download verbose logs using this process.

  1. Go to LuCI page for custom system commands (or in LuCI menu System→Custom Commands )
  2. Click to Download button under Print debug log (Number 3 in Picture 2) and save the log file.

4. Send the logs to support

Follow instructions on page Error reporting and send your logs to support. Please note that procedure listed above supersedes part Getting logs on page Error reporting :-)