The data does not always rush through the network at maximum speed. With our tips and tools you can measure the pace and remove the brake pads.
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You have connected your desktop PC to a router or switch using an Ethernet cable and, under Windows 11, you can, for example, copy your photo or video collection to a network storage device or a share on another computer. But you are far from the nominal speed. Instead of the possible 100 MB per second in your gigabit network, the file manager shows far less speed. Now it is important to find the cause of the throttling and to eliminate it permanently.
View Windows network speed information
The first way to investigate the cause is via the Windows 11 Settings app, which you can open most quickly with the Windows-I key combination. Click on “Network & Internet” on the left side of the window. In the right window area you will see five areas and at the very top right next to the large symbol “Ethernet – Connected”. You can open the information that is now relevant by clicking on “Advanced network settings”. At the top of the window you will then see the network card installed in the PC under “Ethernet” – in our example “Network | Intel (R) PRO / 1000 MT Desktop Adapter “. The name suggests that the network card is capable of gigabit speeds. A click on the arrowhead to the right of “Deactivate” shows further details. The connection speed is important here: “1000 (Mbps)” is displayed here to match the card. With a 2.5GBase-T card, this is “2500 (Mbps)”. For more information on the connection speed “Receive and transmit”, click on “Show additional properties”.
You can now assume that the PC, at least in theory, can handle the expected network speed. However, since it cannot do this in a reproducible manner in practice, you should continue investigating the cause.
Measure real speed with Windows on-board tools
You already got the first information about the speed of your network when copying files in the Explorer of Windows 11 or a file manager like Speedcommander and Total Commander or a copy tool like Teracopy. Now determine the speed in different scenarios: In our example there is a NAS from Synology, a NAS from Qnap, a network storage device from Western Digital and a network share on a notebook. Now transfer the same mixed selection with small and large files to the existing devices one after the other. Use a stopwatch to measure the time it takes Explorer to transfer the files from the source to the destination. Ideally, repeat this process three times and then determine the average value.
Then carry out measurements with 50 small files (each <5 MB) and then with a large file (> 4 GB). This ensures a realistic result.
When transferring data via TCP / IP, the files are not transferred in a block in the network from the source to the destination, but are divided into many small packets. Each package is stored with the name of the file and its path in the file system, among other things. Naturally, this is faster with a large file than with many small files. After all the measurements, you can assess the speed of your network under practical conditions. With Gigabit Ethernet, for example, the theoretical data transfer rate is 1 GBit per second and the data throughput is 940 MBit per second. This corresponds to about 117 MB per second. If the values are well below the average values of a fast network, the search for the causes of the speed brakes continues.
Windows 11 shows in the Settings app whether your PC is capable of gigabit speeds at all.
The freeware Iperf is the standard tool for measuring network speed. In addition to the command line program, there is also a version with a graphical user interface under the name Jperf. Unzip the ZIP file and double-click on the “jperf.bat” file to start the setup.
Repeat this process on a second computer in your network. Make one of these two PCs the Jperf server and mark the corresponding option in the upper part of the program window. Open the “Command Prompt” on this PC and use the ipconfig command to determine the IP address of the network adapter. Switch back to Jperf and click “Run Iperf!” To start the server. On the other PC, make sure that Jperf is configured as “Client” there. Enter the IP address of the server next to “Server address”. Set a time of 30 seconds in the “Application layer options” area next to “Transmit” and select the “MBits” option as the unit in the “Output Format” drop-down menu. Then start the test by clicking on “Run IPerf!”.
Check network hardware
For maximum network speed, the hardware must match each other – i.e. router, switch, network card in the PC and of course the cables between the individual devices. For example, if an old 100 MB switch is in the network, it slows the speed down to a tenth of what is possible in a gigabit network. So first check the individual network devices. They should consistently support at least 1000 Mbit per second (1 GBit).
Then pay attention to the labeling of the network cable. In principle, Cat 5 cables enable a transmission speed of up to 1000 Mbit per second. However, network cables of the more expensive categories Cat 6 and Cat 7 offer significantly better shielding against interference and thus against a noticeable drop in speed.
PC tuning without any hardware upgrade