fix(instances): Document api-metadata as a cause of problem with SSH keys

Author: Louis Bouchard

pages/instances/troubleshooting/fix-common-issues.mdx

@@ -84,6 +84,7 @@ This page lists the most common issues you may encounter with your Scaleway Inst
 - Wrong username: Using `root` versus a custom user.
 - Misconfiguration of the SSH daemon: `sshd_config` might disallow key-based authentication.
 - Key not installed: The public key might not have been successfully added to the Instance.
+- No access to Scaleway's api-metadata : Api-metadata is responsible for loading the SSH keys.
 
 ### Solution
 - Check file permissions locally:
@@ -100,6 +101,16 @@ This page lists the most common issues you may encounter with your Scaleway Inst
 - Re-add your SSH Key in the Scaleway console:
    - Go to the [SSH keys](https://console.scaleway.com/project/ssh-keys) tab in the **Project** section of theScaleway console, remove the old SSH key, then add your new, correct public key.
    - Restart your Instance to re-upload the list of allowed SSH keys.
+- Confirm that your instance has access to the api-metadata by using the serial console
+   - Execute the following :
+     ```bash
+     # curl http://169.254.42.42/
+     ```
+     The response should be
+     ```json
+     {"api": "api-metadata", "description": "Metadata API, just query http://169.254.42.42/conf or http://169.254.42.42/conf?format=json to get info about yourself", "version": "12.23.0"}
+     ```
+     Otherwise you need to identify why the access to api-metadata is blocked somehow.
 
 ### Additional resources
 - [Scaleway Documentation: How to generate an SSH key pair](/organizations-and-projects/how-to/create-ssh-key/)
@@ -287,4 +298,4 @@ This page lists the most common issues you may encounter with your Scaleway Inst
 ## Next steps
 
 - Always consult the official [Scaleway Instances Documentation](/instances/) for detailed, up-to-date information to troubleshoot your Instance.
-- If you are still experiencing issues after following these tips, open a [support ticket](https://console.scaleway.com/support) in your Scaleway console, providing detailed descriptions of your issue, logs, screenshots, or error messages. This will help the Support team diagnose and resolve your issue more quickly.
+- If you are still experiencing issues after following these tips, open a [support ticket](https://console.scaleway.com/support) in your Scaleway console, providing detailed descriptions of your issue, logs, screenshots, or error messages. This will help the Support team diagnose and resolve your issue more quickly.