Troubleshooting Network Issues

For the latest information on any disruptions, visit our status page: https://www.netcup-status.de

The following characteristics may indicate problems with your server:

• Increased ping times of 100 milliseconds or more.
• Packet loss on the route to the vServer, possibly even at the last node.

Check your network connection and send us the results.

1. Checking the Firewall

Check whether the firewall is blocking the application you are using. To do so, remove all policies and restart the application.

Alternatively, you can create an allow-all policy:

1. In the Server Control Panel (SCP), go to Options > Firewall Policies.
2. Click Add Firewall Policy.
3. Add two rules for each protocol type:
   • Incoming: ACCEPT
   • Outgoing: ACCEPT

Ensure that the allow-all policy is in the first position. You can move the policy up using drag and drop.

2. Activating the Rescue System

Boot your server into the rescue system.

Please note that it is necessary to perform these tests while the rescue system is active. This will rule out any problems at operating system level.

3. Running dhclient

The dhclient command checks whether your server receives an IP address from the DHCP server.

Execute the following command:

dhclient -v <Networkinterface>

The default network interface is usually eth0. Different names can be determined using ip a.

4. Running MTR

Use MTR (My Traceroute) or WIN-MTR to check for packet loss on the route to the nodes. Execute at least 500 pings on both the server and the corresponding host using the terminal command below: mtr <server_ip>

You can find the server IP in the Server Control Panel (SCP) under Network.

Make sure the netcup Ping allow firewall rule is activated. If you have deleted it, click Restore Default Policies under Firewall in the Server Control Panel (SCP).

Please note that we need a My Traceroute instead of a regular Traceroute for analysis purposes, given that My Traceroute is much more detailed.

5. Running iperf3

Next, run iperf3 via the terminal. This will provide us with information about the connection and speed to and from your server. Make sure that the firewall port 5201 TCP (default port) is open.

6. Reporting to netcup

Contact Customer Support. Your ticket should contain the following information:

• Your customer number
• The server name and IP address
• The output of dhclient
• The output of MTR
• The output of iperf3
• Information on whether the rescue system was booted

To help us process your ticket, please provide the requested information as a text file in the attachment. We will then process your request as quickly as possible.