--- title: "How to Test Your VPS's Bandwidth" description: "Test your Winheberg VPS's bandwidth with Speedtest and iperf3, and learn how to properly interpret your results." category: vps subcategory: vps-linux icon: tabler:file-text date: 2026-07-24 author: Winheberg slug: "test-vps-bandwidth" order: 4 image: /statics/images/docs/en/vps-linux/test-vps-bandwidth.webp tags: [vps, bandwidth, speedtest, iperf3] keywords: [test vps bandwidth, speedtest cli linux, iperf3 throughput test, moji paris server, winheberg vps performance] link_fr: "/docs/vps-linux/tester-bande-passante-vps" --- ## Context You just rented your **Linux VPS** at Winheberg and want to **check your server's network performance**? Or maybe your applications seem slow and you want to know if the issue comes from bandwidth? Testing your VPS's throughput is a simple, useful step that takes just a few minutes with the right tools. This guide covers the **two go-to tools** for measuring your server's bandwidth, along with best practices for interpreting the results. It works on every distribution we offer, Debian 11/12/13, Ubuntu 23.10/24.04/25.04, AlmaLinux 9/10, Rocky Linux 9/10, Fedora 41/42, and Alpine Linux 3.22. ## Why test your VPS's bandwidth? Several reasons might lead you to measure your server's throughput. - **Verify the advertised performance** at the time your VPS was delivered - **Diagnose slowness** on a site, an application, or a hosted service - **Compare several hosts** or several plans against each other - **Test connectivity** to a specific region or country - **Detect network saturation** if your server hosts many services Before you start, keep in mind that a bandwidth test measures the **instant throughput** between your VPS and another point on the Internet. Results can vary depending on the time of day, the test destination, and overall network load. ## Which tool should you choose, Speedtest or iperf3? There are two main tools for testing a VPS's bandwidth, each with its own strengths. **Speedtest** is the official **Ookla** command-line tool. It's the pro version of the well-known **Speedtest.net**. It tests your VPS's speed toward the Internet by automatically connecting to a geographically nearby Speedtest server. It's the ideal tool for a **quick, representative** measurement of real-world internet throughput, with a result you can easily share. **iperf3** is a more technical, precise tool that measures throughput between two machines (your VPS and a remote iperf3 server). It's particularly useful for **testing a specific route**, saturating a connection with multiple streams, or more in-depth network performance measurements. > [!TIP] > Use both tools. Speedtest for a quick, general-purpose overview, iperf3 for more focused tests toward specific servers. ## Method 1. Test with Speedtest (official Ookla) This is the simplest and fastest tool. It mimics what you'd do on **speedtest.net** from your browser. We recommend the **official Ookla version**, more up to date and reliable than the older Python `speedtest-cli`. ### 1. Install Speedtest :::MdTabs ::MdTab{label="Debian and Ubuntu"} First install curl if not already done, then add the official Ookla repository and install the package. ```bash apt install curl -y curl -s https://install.speedtest.net/app/cli/install.deb.sh | bash apt install speedtest -y ``` :: ::MdTab{label="AlmaLinux, Rocky Linux, and Fedora"} ```bash dnf install curl -y curl -s https://install.speedtest.net/app/cli/install.rpm.sh | bash dnf install speedtest -y ``` :: ::MdTab{label="Alpine Linux"} The official Ookla version isn't available on Alpine, but you can use the older Python version. ```bash apk add speedtest-cli ``` > [!WARNING] > `speedtest-cli` is an older Python project, less optimized and less actively maintained than the official Ookla client. Results may be less accurate and the test slower to run. Use it knowingly on Alpine, in the absence of an official alternative. :: ::: ### 2. Run a test Once installed, run the command specifying directly the **Moji server in Paris (ID 62035)** that we recommend. ```bash speedtest -s 62035 ``` > [!NOTE] > On first launch, Speedtest will ask you to accept Ookla's terms of use and license. Type `YES` then Enter to confirm, this only needs to be done once. The tool will measure **ping**, **download**, and **upload**, and will also give you a **shareable link** at the end of the test. ``` Speedtest by Ookla Server: moji - Paris (id = 62035) ISP: WINHEBERG Latency: 6.35 ms (0.05 ms jitter) Download: 11865.14 Mbps (data used: 15.4 GB ) Upload: 3664.47 Mbps (data used: 6.5 GB ) Packet Loss: 0.0% Result URL: https://www.speedtest.net/result/c/577533f5-507f-427d-9cca-31ba238cef6e ``` The **Result URL** shown at the end is a shareable link with a visual chart. You can send it to our support if you need help analyzing a result. > [!TIP] > Speedtest can automatically pick a server, but the result then varies from one test to another. By forcing the **Moji Paris** server, you get a reliable, reproducible measurement, perfect for comparing tests over time. ### 3. Test toward another server If you want to compare connectivity to another point in the world, you can use any other Speedtest server. To list the servers available nearby. ```bash speedtest --servers ``` You'll get a list of servers with their **ID**. To test toward a specific server, use the same syntax. ```bash # Example, test toward the Moji Paris server (our recommendation) speedtest -s 62035 ``` ## Method 2. Test with iperf3 iperf3 is more precise and lets you test specific routes between two servers. ### 1. Install iperf3 Installation is similar depending on your distribution. :::MdTabs ::MdTab{label="Debian and Ubuntu"} ```bash apt install iperf3 -y ``` :: ::MdTab{label="AlmaLinux, Rocky Linux, and Fedora"} ```bash dnf install iperf3 -y ``` :: ::MdTab{label="Alpine Linux"} ```bash apk add iperf3 ``` :: ::: ### 2. Run a test against a public iperf3 server iperf3 needs a **remote server** to send test packets to. We recommend the **Moji** server in Paris, which offers excellent bandwidth and is very close to our datacenters. ```bash iperf3 -c iperf3.moji.fr -p 5200 ``` > [!TIP] > The Moji server offers several ports between **5200 and 5240**. If one is saturated, try the next one (5201, 5202, etc.) to get an available slot. The test runs for about **10 seconds** by default, then shows the average throughput. ``` Connecting to host iperf3.moji.fr, port 5200 [ 5] local 51.158.xx.xx port 54312 connected to 89.xxx.xxx.xxx port 5200 [ ID] Interval Transfer Bitrate Retr Cwnd [ 5] 0.00-1.00 sec 118 MBytes 990 Mbits/sec 0 412 KBytes [ 5] 1.00-2.00 sec 119 MBytes 998 Mbits/sec 0 412 KBytes ... - - - - - - - - - - - - - - - - - - - - - - - - - [ ID] Interval Transfer Bitrate Retr [ 5] 0.00-10.00 sec 1.16 GBytes 997 Mbits/sec 0 sender [ 5] 0.00-10.00 sec 1.16 GBytes 994 Mbits/sec receiver ``` ### 3. Test in both directions By default, iperf3 measures **upload** (you send data to the remote server). To also test **download**, add the `-R` option (*reverse*). ```bash iperf3 -c iperf3.moji.fr -p 5200 -R ``` ### 4. Test over IPv6 If your VPS has an IPv6 address and you want to test IPv6 connectivity specifically, use the `-6` option. ```bash iperf3 -c iperf3.moji.fr -p 5200 -6 ``` ### 5. Test in parallel to saturate the connection To really see your VPS's **maximum bandwidth**, run several parallel streams with the `-P` option. ```bash iperf3 -c iperf3.moji.fr -p 5200 -P 4 ``` Here, 4 parallel streams are sent simultaneously. The total throughput is the sum of the 4 streams. ### 6. Test for a longer duration By default, the test runs for 10 seconds. For a more stable measurement, increase the duration with `-t`. ```bash iperf3 -c iperf3.moji.fr -p 5200 -t 30 ``` The test will now run for 30 seconds, giving a more representative average. ### 7. Test toward other destinations The Moji Paris server is perfect for measuring your VPS's raw performance, but if you want to test connectivity to another region of the world, the community maintains a list of **public iperf3 servers sorted by continent** at [github.com/R0GGER/public-iperf3-servers](https://github.com/R0GGER/public-iperf3-servers#servers-per-continent). Find a server close to the destination you're interested in, then run your test with its address and port instead of `iperf3.moji.fr`. ```bash iperf3 -c server-address -p port ``` > [!NOTE] > These servers are run by third parties, their availability and performance don't depend on Winheberg. Some may be temporarily down or saturated, the GitHub list is updated regularly to remove servers that no longer respond. ## Interpreting the results Results can vary a lot depending on several factors. Here's how to analyze them correctly. ### The expected throughput On our VPS plans, you get bandwidth suited to each tier. If your test gives results well below what's advertised, several reasons are possible. ### The time of the test Bandwidth can vary depending on the time of day. During peak hours (evenings especially), the global Internet network is more loaded, which can lower measured throughput toward certain destinations. ### The test destination The measured throughput can vary a lot depending on the remote server you're testing against. Several factors come into play. - **Geographic location**, testing toward a server on the other side of the world will always give lower results than a test toward a server in the same country, due to physical distance and the number of network hops - **Internet transit**, to reach a remote server, your traffic passes through several transit operators (Cogent, Level3, Telia, etc.), each operator has its own capacity limits, and a test can be throttled by one of them with no connection to your VPS - **Peering**, hosts and operators negotiate peering agreements with each other to exchange traffic directly, without going through transit operators, good peering toward a destination gives excellent results, poor peering can drop throughput even over short distances - **Latency (ping)**, the higher the latency, the harder it becomes to saturate a high-speed connection over TCP (due to how the protocol itself works), that's why you sometimes get 10 Gbps locally and only 2 Gbps toward another continent That's why we recommend testing first toward a geographically close server (Moji Paris for French users) to measure your VPS's raw performance, then optionally testing toward other destinations if you want to check connectivity to a specific region. ### The protocol used By default, iperf3 and speedtest-cli use **TCP**. If your application uses **UDP**, the results may differ. To test over UDP with iperf3, use the `-u` option. ```bash iperf3 -c ping.online.net -p 5202 -u -b 1G ``` ### Your VPS's load If your VPS is heavily loaded on CPU or RAM at the time of the test, this can skew the results. Remember to check the load with `htop` before running a test. ## If you run into trouble Here are the most common errors and situations you might run into. ### ❌ speedtest, command not found The package isn't installed, or the installation stopped before finishing. Redo the installation step matching your distribution. ### ❌ iperf3, error unable to connect to server The iperf3 server may be saturated or blocking connections on that port. Try another port between 5200 and 5240, or try again a few seconds later. ### ❌ Results well below expected performance Check your VPS's **CPU load** with `htop`. If the CPU is at 100%, the test won't be able to saturate the connection. Also consider testing with **several parallel streams** (`-P 4` with iperf3) to really see the maximum throughput. ### ❌ Speedtest asks to accept a license every time On first launch, you need to accept Ookla's terms by typing `YES`. If the prompt keeps coming back every time, the configuration file isn't being saved. Run the command with `--accept-license --accept-gdpr` to confirm it once and for all. ```bash speedtest --accept-license --accept-gdpr ``` ## Need help? If your bandwidth results seem abnormally low or you suspect a network issue on your VPS, our team is here. Open a ticket in the **Technical** department from your client area, fill in the **Related Product** field with the VPS in question, and attach your test results. You now know everything you need to precisely measure your VPS's network performance 📊