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Knowledge document #3600
FRITZ!Box 5490
This support document is available for the following products:

FRITZ!Box does not establish a fiber optic connection

Although the FRITZ!Box was configured for use with a fiber optic line, the FRITZ!Box does not establish a fiber optic connection. The message "Fiber interrupted" is displayed on the "Overview" page of the FRITZ!Box user interface. The message "Fiber cable not connected" may be displayed in the "Fiber Information" of the FRITZ!Box.

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

1 Making sure that the fiber optic connection is supported

  1. Check the documentation for your fiber optic connection or ask your internet service provider whether it is an active fiber optic connection according to the standard ITU-T G.652 (AON). It is not possible to use the FRITZ!Box with a passive fiber optic network (ITU-T G.984, GPON).

2 Checking the cabling

  1. Remove all cable extensions and adapters between the FRITZ!Box and the fiber optic socket.
  2. Use an undamaged cable to connect the FRITZ!Box with the fiber optic socket. The fiber optic cable may not have any kinks or be damaged. For detailed information, refer to the quick guide included with the FRITZ!Box and the manual.

    Note:The FRITZ!Box has an SC/PC connector (wide connector, flat endface). Depending on the fiber optic socket, you may need to use a fiber optic cable with an adapter. The fiber optic cable is not included in your FRITZ!Box package.

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

Install the latest version of FRITZ!OS because it contains improvements for different fiber optic connections that can resolve the error:

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

4 Contacting your provider

If the FRITZ!Box still does not establish the fiber optic connection, there may be a problem with the fiber optic line:

  1. Contact your internet service provider.
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