I am based in Germany. I have recently got a new 100 Mbit/s internet connection.

My new Router is a Fritz!Box 7490, with Wifi speed 1300 + 450 Mbit/s in 2.4 and 5 GHz.

My wireless network card in my desktop PC is a TP-Link TL-WN781ND WLAN PCI-E Adapter (150Mbits/s, Windows 8.x / Vista / 7 / XP) , with up to 150 Mbit/s (so, still 1.5x the speed of the internet that comes out of the wall).

Now, when I use an ethernet cable to connect the PC (Windows 8) to the router, the download speed is approx. 11 MByte per second, so very close to the 100 MBit maximum. The Ethernet cable goes into the mainboard, an ASUS Z97-K.

The same computer, download applications, etc. only achieves approx. 6 MByte/s when connecting to the router using Wifi.

I also used a directional Wifi-Antenna directed at the router, with no improvement. However, the PC and the router are just 3-4 meters from each other in the same room anyway.

As far as I can see, all hardware should be capable of achieving speed well beyond 100 MBit/s, therefore the bottleneck for the Wifi speed should be the internet speed "in the wall", and not any of the Wifi-hardware between the wall and my PC.

What can be the reasons, and how can I improve the Wifi speed?


Wifi speed is hit and miss and depends on a lot of factors.

  1. Just because you have a high speed router does not mean that the wifi card in your laptop supports those speeds. You might have a 450Mbps router, but only support 54Mbps on your wifi card. You need to check your wifi card specifications and make sure it claims the same speed and wifi specifications as your router.

    Older wifi cards cannot work at the same speeds as newer devices, they simply lack the hardware support for newer encoding schemes and speeds.

    It is possible that your 150Mbps card uses some custom mode that is only supported by a particular group of networking devices and falls back to a slower mode for compatibility with the wider market. In the early days of fast wifi this was not entirely uncommon.

  2. Wifi is adversely affected by a lot of electronic devices. The frequency range used by wifi is actually a "free for all" band that can be used by any devices for whatever purpose they like, subject to power limitations. To name a few:

    • Mobile phones (bluetooth & wifi),
    • microwave ovens,
    • other wifi routers,
    • cordless phones,
    • baby monitors
    • radio controlled drones
    • IoT home monitoring devices (cameras, doorbells, etc)
  3. Using wireless signals the signal is effectively half-duplex while ethernet is full duplex. Ethernet has separate data lines for transmitting and receiving data and can do both at the same time, wifi cannot, it has only one effective "wire".

    What this means is that every time your router needs to send your computer data it must wait for your computer to stop transmitting before it can respond. This means that the theoretical 150Mbps is somewhat optimistic when used in a real world environment. Local noise listed in 2 can seriously degrade speeds.

    It might be that burst transmissions happen at 150Mbps, but the overall speed over a longer period is half of that or worse depending on noise.

You can improve speeds by using applications on your phone to scan for other wifi networks and changing the channel number on your router to avoid other networks. Bear in mind though that for 2.4GHz the only channels that should be used are 1, 6 and 11. All other channels overlap with multiple other channels and can mean worse signal than just overlapping with one of the currently used channels.

You can also buy a newer wifi card with better support for newer standards, USB ones are quite cheap these days.

If you care about speed or latency then do not use wifi.

  • I have disabled the WiFi-Card in Window's device manager, and purchased a USB-connected FRITZ!WLAN Stick AC 860. It now achieves a consistent 10-11 MB/s. – Marie. P. Mar 11 at 11:12

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