Troubleshoot connection to cloud instances

If you cannot connect to your cloud instance via SSH, the issue is usually related to a common configuration problem.

You can use the troubleshooting steps below to identify and resolve the issue. We recommend starting with the quick checks first.


  • Quick checks

    Before troubleshooting further, confirm the following:

    • The instance status is Active
    • The instance power state is Running
    • The security group allows SSH (port 22) inbound traffic
    • The correct instance username is used
    • The correct private key is used

    If these checks are correct and you still cannot connect, continue with the steps below.




  • Common error messages

    The table below lists common SSH error messages, the likely cause, and what you should check.

    Follow the troubleshooting sections below to resolve these issues.

    Error Message Likely cause
    		 Suggested Action
    Connection timed out SSH traffic blocked Check security group rules
    Connection refused SSH service is not reachable or instance not running Check instance status and IP
    Connection closed by [instance] port 22 Authentication failed or SSH service closed the connection Check instance username and private key
    Host key verification failed The host key stored locally does not match the instance Remove entry from known_hosts
    Network is unreachable Incorrect IP address or network issue Check the instance IP address
    No supported authentication methods available SSH authentication failed Check instance username and private key
    Permission denied (publickey) Incorrect key or username Check username and private key
    Permission too open Private key permissions are too permissive Check private key permissions
    Please log in as the user “X” rather than the user “Y”. Incorrect username used for the operating system Check instance username
    Private key must begin with… Private key is not in valid PEM format Check private key format
    Unable to load key Private key format or file path is incorrect

    Check private key format
    Unprotected private key file Private key permissions are too permissive

    Check private key permissions
    User key not recognised by server Incorrect private key used

    Check private key
    Server refused our key SSH key authentication failed

    Check private key and username





  • Check security group rules

    Security groups control which network traffic is allowed to reach your instance.

    To connect via SSH, the instance must allow inbound traffic on port 22.

    The default security group already includes a rule allowing SSH access.

    If your instance is using a custom security group, ensure it includes a rule allowing:

    • Protocol: TCP
    • Port: 22
    • Direction: Ingress

    If the rule restricts traffic to a specific IP address or range, ensure your current IP address is allowed.





  • Check the SSH command

    Ensure the SSH command used to connect is correct:

    ssh -i /path/privatekey.pem username@ip-address

    Example:

    ssh -i ~/.ssh/mykey.pem ubuntu@154.65.100.23

    The file path in the command must be correct. 

    • This should be the fully-qualified path to the location on your computer.
    • The file type (default .pem) must be included.

    You should also check:

    • The username matches the instance operating system.
    • The IP address matches the instance

    Note: SSH uses port 22 by default, so specifying -p22 is not usually required.





  • Check the instance username

    A connection error can occur if the incorrect username is used.

    When connecting for the first time, you must log in using the default username for the instance image.

    These are the default usernames for the xneelo Cloud public images.

    OS Name Default username
    AlmaLinux almalinux
    CentOS cloud-user
    Debian debian
    Ubuntu ubuntu

    If you are using a different operating system image, the default username may differ.





  • Check the private key

    The private key used to connect must match the key pair assigned to the instance when it was created.

    Common problems include:

    • Selecting the wrong private key file
    • Using a key from another instance
    • The key file being corrupted or incomplete

    Ensure the correct private key file is used in your SSH command.





  • Check the private key format

    SSH keys used with xneelo Cloud are typically stored in .pem format.

    The file should begin with a line similar to:

    -----BEGIN RSA PRIVATE KEY-----

    If the key does not follow this format, it may not work with SSH.

    If you are connecting using PuTTY on Windows, the private key must be converted to .ppk format using PuTTYgen.






  • Check the instance IP address

    Verify that the IP address used in your SSH command matches the instance public IP address.

    You can find the IP address in: Compute > Instances.

    Both IPv4 and IPv6 addresses may be available.

    If you are using IPv6 and cannot connect, try the IPv4 address instead. Some Internet Service Providers (ISPs) do not support IPv6 connectivity.





  • Host key verification failed

    This can occur if the instance was rebuilt or its SSH host key changed.

    SSH stores known hosts in the following file:

    ~/.ssh/known_hosts

    You can remove the entry for the instance from this file and attempt to connect again.

    The error message you received should display the line number corresponding to the host instance (IP address will be displayed). You will need to remove this line from the known-hosts text file.

    You can either remove this from the file manually, or via command line. In this example, the offending line is line 76.

    sed -i '76d' ~/.ssh/known_hosts





  • Check the instance status or reboot


    Your instance must be running before it can accept SSH connections.

    Steps

    1. 1
      Navigate to Compute → Instances.
    2. 2
      Locate your instance in the table.
    3. 3
      Confirm:
    • Status: Active
    • Power State: Running

    If the instance is stopped or paused, start or reboot the instance.





  • Check the instance console log

    If the instance is running but still unreachable, check the console log.

    The console log displays system messages generated during instance startup.

    These logs may reveal issues such as:

    • network configuration errors
    • missing network interfaces
    • cloud-init failures
    • disk or filesystem errors

    Review the console output for error messages that may explain why the instance cannot accept connections.

    By default, the last 35 lines of the console’s output will be displayed. However, you may need to view the full log to find the error.





  • Consider recent changes


    If an instance was previously accessible but is now unreachable, consider recent changes that may have caused the issue.

    Examples include:

    • Changing security group rules
    • Introducing  firewall rules
    • Modifying network configuration
    • Performing system upgrades
    • Editing configuration files that affect boot or networking

    Reverting recent changes may restore connectivity.



Assist Note

If you still cannot connect after following the troubleshooting steps above, contact support and include:

  • The error message you received
  • The SSH command you used
  • The instance IP address

Please note that xneelo Cloud is a self-managed product, and support may not be able to assist with operating system configuration issues inside the instance.

You can read more about our support in xneelo Cloud.

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