Troubleshooting Dedibox network issues

Problem

To diagnose network issues, you need to perform a series of tests.

Symptoms

• Slow network speeds
• High packet loss
• Unstable connections

Possible Causes

• Network congestion
• Hardware issues
• Misconfigured network settings

Solution

Use MTR and iPerf tests to analyze network performance.

MTR Test

An MTR test combines the functionality of traceroute and ping to examine all points between two machines.

When performing an MTR test, it is important to run it in both directions:

• From your server to your connection's IP
• From your connection to the server

On Linux

Ensure the mtr package is installed:

sudo apt-get install mtr

or

sudo yum install mtr

On Windows

1. Download the application from its project page.
2. Extract the archive and run the executable.
3. Enter the target IP in the Host text box, then click Start. Wait one or two minutes before stopping the test. You can take a screenshot or export the results using the software's built-in functions.

Example of an MTR test between a Scaleway Dedibox server and free.fr

root@163-172-30-2:~# mtr --report free.fr
Start: Sun May  1 16:23:57 2016
HOST: 163-172-30-2                Loss%   Snt   Last   Avg  Best  Wrst StDev
1.|-- 163-172-30-1.rev.poneytel  0.0%    10    0.5   0.5   0.4   0.5   0.0
2.|-- 195.154.1.248              0.0%    10    1.6   1.0   0.9   1.6   0.0
3.|-- 195.154.1.254              0.0%    10    1.2   1.4   1.2   2.6   0.3
...

Key metrics:

• Loss%: Percentage of lost packets
• Snt: Number of packets sent (here, 10)
• Last: Latency of the last packet sent
• Avg: Average latency for all packets sent
• Best: Lowest recorded latency
• Wrst: Highest recorded latency

iPerf test

An iPerf test helps measure the available bandwidth of your server.

The iPerf server ping.online.net offers several ports (5200-5209). If the default port is busy, specify another port using the -p flag, e.g., -p 5203.

On Linux

If iPerf is not installed, install it using:

sudo apt-get install iperf3

or

yum install iperf3

Run the test:

root@163-172-30-2:~# iperf3 -c ping.online.net -R
------------------------------------------------------------
Client connecting to ping.online.net, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  3] local 163.172.30.2 port 36490 connected with 62.210.18.40 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  1.10 GBytes   943 Mbits/sec

On Windows

1. Download iPerf from its website.
2. Choose the latest version and download the file.
3. Extract the file.
4. Open a terminal and run:
   iperf3.exe -c ping.online.net -p 5203

Key metrics:

• Interval: Sampling interval in seconds
• Transfer: Amount of data transferred
• Bandwidth: Available bandwidth

If your server’s network port is off

If you change your dedicated server's mode (e.g., from normal to rescue mode) during a reboot, you may see the following error in your console:

If this message appears repeatedly or for long periods, your server may be sending unauthorized DHCP traffic, an unassigned MAC address, excessive ARP requests, or too many requests per second.

If the message persists, try clearing your browser cache or reloading the page multiple times.