This article explains how to collect information about your system and possible sources of error when your Cloud Server fails.

If your server is no longer accessible, please first try to exclude possible sources of error step by step in order to identify and eliminate the cause as quickly as possible. Proceed as follows:


If you have network problems with your server, IONOS customer service may ask you to run the MTR diagnostic tool to collect further information. MTR (My Traceroute) combines the tools ping and traceroute. For instructions on installing MTR and running tests, see the following article:

Using MTR for Network Diagnostics

When troubleshooting network latency issues, we first ask you to check your server for configuration issues, updates, plugins, custom program code, and other settings. Instructions for collecting the information that IONOS customer service needs for troubleshooting can be found in the following article:

Required Information for Network Tickets

Restart and check connection to the server


Depending on the operating system and configuration of the server, this process can take up to 10 minutes.


Check the Log Files

If you can establish a connection to your server, check the server's log files. When troubleshooting, consider updates and configuration changes that may have been made recently.

If you cannot connect to your server, continue to the next step.

Check the Firewall Policy and Rules

  • In the Infrastructure > Servers section of the Cloud Panel, check which firewall policy is assigned to the server. 

  • In the Network > Firewall Policy section, check if the required ports have been opened in the assigned firewall policy. If necessary, assign the correct firewall policy to the server or create the necessary rules for the port releases in the assigned firewall policy, such as port 22 for SSH or port 3389 for RDP.

  • Try again to connect to the server via SSH  (Linux) or Remote Desktop (Microsoft Windows Server).

Perform a Port Scan

If you cannot connect to the server after checking and, if necessary, adjusting the firewall policy in the Cloud Panel, perform a port scan. Check whether Port 22 (Linux) or Port 3389 (Microsoft Windows) are enabled.


If you are using Linux, you can use the netcat program to perform a port scan. Netcat (nc), is a universal command line tool. It can be used in the terminal or in scripts for communication via TCP and UDP network connections (Internet Protocol version 4 and version 6).

The netcat program is a part of every Ubuntu installation, but can be installed using the following commands when necessary.

[root@localhost ~]# apt-get update
[root@localhost ~]# apt-get install netcat

To install netcat on a server with the distribution CentOS, enter the following command:

CentOS 7, CentOS Stream 8 and 9

[root@localhost ~]# yum update
[root@localhost ~]# yum install -y nc 

To perform a port scan with netcat, enter the following command:



[root@localhost ~]# nc -v 22

Microsoft Windows

To perform a port scan in Windows, enter the following command in the Powershell on your local computer:



[root@localhost ~]# Test-NetConnection -Port 22



If the required ports are blocked even after checking and, if necessary, adjusting the firewall policies, a check of the firewall settings in your operating system is required.

Check the Configuration of the Server

If you cannot connect to the server, log in to the server using the KVM console. Then check the network settings of the server.

The most important commands you need to check the network configuration can be found in the following article:

Checking the firewall configuration and the network settings (Linux)

Use Knoppix for Data Rescue If Access to the Operating System Is Not Possible

If you cannot access the operating system, you can boot your server using the Knoppix DVD and mount the partitions so that you can access the data via SSH or SFTP. Simply follow these steps:

In the Cloud Panel, insert the Knoppix DVD in the Infrastructure > Server section and restart the server. The server now boots with the Knoppix-DVD. The server now boots with the Knoppix DVD. After the restart of the the server, you can access Knoppix through the KVM console and create a backup of your data or change the configuration of your server. Step-by-step instructions can be found here:

Cloud Server: Use Knoppix for data recovery


If your server cannot boot with the Knoppix DVD or if you have problems with troubleshooting, please contact support.