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FRITZ!Box reports "Interference may have been caused by powerline"

The FRITZ!Box's VDSL connection drops frequently or the DSL data rate is significantly lower than the DSL speed guaranteed by the internet service provider as soon as powerline devices connect to the FRITZ!Box. The Power/DSL LED on the FRITZ!Box flashes when the connection drops and then stays lit as soon as the internet connection is re-established. One of the following error messages is displayed in the event log of the FRITZ!Box:

  • "The internet connection (DSL) was cleared. Interference may have been caused by powerline."
  • "The DSL signal may have been distorted by powerline."


  • Powerline is disturbing the VDSL connection. Since the frequencies used by VDSL and powerline partially overlap, both technologies can interfere with each other.

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 Checking the cabling

  1. Plug the powerline device directly into a wall outlet. Do not use a power strip or an extension cord.
  2. Lay the DSL cable at a distance of at least 10 cm away from electrical wiring and outlets. The greater the distance between electrical wiring and the DSL cable, the better.
  3. Do not roll cables and avoid loops in the cables ("cable spaghetti").
  4. Test whether you can solve the problem by positioning the powerline device connected to the FRITZ!Box farther away from the DSL connection. For example, plug it into a different wall outlet.

2 Running malfunction detection

  1. Click "Internet" in the FRITZ!Box user interface.
  2. Click "DSL Information" in the "Internet" menu.
  3. Click on the "Interference Resistance" ("Line Settings") tab.
  4. Click "Interference Resistance Settings" to display all of the settings.
  5. Click on the "Detect and Resolve Malfunctions" button. Now the FRITZ!Box checks the powerline connections and attempts to resolve problems with the DSL connection.
  6. If the button "Detect and Resolve Malfunctions" is still shown after running the test, repeat the test until no further improvement of the DSL connection is possible.
  7. When you have finished testing, click "Finished".