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Knowledge document #3337
FRITZ!Box 6840 LTE
This support document is available for the following products:

Throughput of the mobile connection is too low

The throughput displayed in the FRITZ!Box user interface for the mobile connection is significantly lower than the speed guaranteed by the mobile network provider.


  • The throughput of the mobile connection depends on factors such as the distance from the mobile station, the shielding effect of the walls of your own house, of neighboring houses, and also trees. Storms and other users located in the same radio cell can also reduce the throughput.

    Important:In many places, you will not be able to fully achieve the guaranteed throughput. This is why mobile network provider say that they offer speeds of "up to" a certain value.

Simply proceed as described below. After each measure, check whether the problem is solved.

Note:All instructions on configuration and settings given in this guide refer to the latest FRITZ!OS for the FRITZ!Box.

1 Installing the latest FRITZ!OS for the FRITZ!Box

Installing the latest FRITZ!OS makes your FRITZ!Box compatible with the latest mobile network technology used by mobile network providers in their radio cells:

  1. Install the latest FRITZ!OS on the FRITZ!Box.

2 Finding the ideal location for the FRITZ!Box

You can use the alignment aid to find the ideal location for the FRITZ!Box and the best position for the mobile network antennas:

  1. Click "Internet" in the FRITZ!Box user interface.
  2. Click "Account Information" in the "Internet" menu.
  3. Select the frequency band "Only 2.6 GHz / band 7" because normally you can achieve a higher data throughput in the 2.6 GHz frequency band than with the 800 MHz frequency band.
  4. Click "Apply" to save the settings.
  5. Click "LTE Information" in the "Internet" menu.
  6. Click on the "Reception" tab.
  7. Click the "Start Alignment Aid" button.
    • Now the current signal strength of the antennas is displayed by the LEDs on the FRITZ!Box (in five levels) and in the user interface.
  8. Select a location for the FRITZ!Box where the signal strength is as high as possible. When doing so, note the following:
    1. Do not set up the FRITZ!Box in the corner of a room.
    2. Place the FRITZ!Box as close to an outside wall as possible. If you know where your provider's LTE radio cell is located, place the FRITZ!Box by the wall facing the LTE radio cell.
    3. Place the FRITZ!Box so that it is as unobstructed as possible, i.e. not directly in back of or under an obstacle such as pieces of furniture or a heater.
    4. Position the LTE antennas of the FRITZ!Box so that they are as perpendicular as possible (90° angle). For example, position one antenna vertically and the other horizontally.
  9. If the quality of the LTE connection in the 2.6 GHz frequency band is not sufficient:
      1. Click "Account Information" in the "Internet" menu.
      2. Select the frequency band "Only 800 GHz / band 20".
      3. Click "Apply" to save the settings.
      4. Click "LTE Information" in the "Internet" menu.
      5. Click on the "Reception" tab.
      6. Start the alignment aid and repeat the adjustment procedure for the FRITZ!Box.

3 Connecting an outdoor antenna

If you are using the FRITZ!Box in an area located on the edge of the radio coverage area (outdoor coverage area) of your mobile network provider or in a building that exhibits a strong shielding effect, the two mobile network antennas included in the package may not be sufficient for optimal radio traffic. In this case, you can increase the transmission and reception power of the FRITZ!Box by using an outdoor antenna (for example on your balcony or mounted on your roof):

4 Contacting your provider

Your mobile network provider may have throttled the mobile connection if a particular data limit was exceeded, or your provider may be experiencing technical difficulties:

  1. Have your mobile network provider check your mobile connection.