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Knowledge document #3817

LAN connection drops frequently

The LAN connection (Ethernet) between the FRITZ!Box and individual or all of the devices connected to the FRITZ!Box drops frequently. When the error occurs, one of the following messages may be displayed on the devices:

  • "A network cable is unplugged."
  • "Network cable unplugged."
  • "You are currently not connected to any networks."

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 event log of the FRITZ!Box

  1. Click on "System" in the FRITZ!Box user interface.
  2. Click on "Event Log" in the "System" menu.
  3. Check whether events also took place before the time when the error occurred, or whether only events are shown that took place after the error occurred.
  4. If events are also displayed that took place before the time the error occurred, proceed with the next section.

2 Installing the latest software for the device

  1. Install the latest software version for the device or the latest driver for the computer's LAN network adapter.

    Note:Since Windows Update often does not offer the latest drivers, install the drivers from the manufacturer's website, for example from the Intel Download Center.

3 Disabling energy-saving functions for the network adapter

  1. If any energy-saving functions are enabled for the computer's LAN network adapter or the device, disable them for testing purposes.

    Note:In Windows, different power saving functions can be set for many network adapters under "Properties > Power Management" in the Device Manager.

4 Disabling EEE (Energy Efficient Ethernet) in the FRITZ!Box

With EEE, network adapters can be put into an energy-saving standby mode, thus also significantly reducing their average power consumption. Since there may be compatibility issues with individual network adapters when EEE is enabled, disable EEE for testing purposes:

Links "Help and Info" and then "FRITZ!Box Support"
  1. In the FRITZ!Box user interface, click on "Help and Info" on the bottom left of the page and then on "FRITZ!Box Support" at the bottom.
  2. Enable the option "Disable EEE (Energy Efficient Ethernet)" in the "Ethernet Compatibility" section.
  3. Click on "Apply setting" to save the settings.

5 Connecting the device directly to the FRITZ!Box

This step is only necessary if the device is connected to the FRITZ!Box's power adapter by means of a hub/switch, powerline device, LAN/Wi-Fi converter, or other device instead of being connected directly to the FRITZ!Box's power adapter:

Connecting a network device to the FRITZ!Box via LAN
  1. Connect the device directly to the LAN port on the FRITZ!Box's power adapter. If possible, use one of the network cables included with the FRITZ!Box.
  2. If the LAN connection to the FRITZ!Box now remains stable, then there is a problem with the intermediary device or its cabling:
      1. Make sure that the intermediary devices function properly.
      2. Update the software / firmware of the intermediary devices.
      3. Use different network cables to connect the devices to the FRITZ!Box's power adapter. Use the shortest possible high-quality network cables (CAT 5e or higher).

6 Testing a different cable

The network cable used to connect the FRITZ!Box's power adapter to the FRITZ!Box or device may be too long, incorrectly wired, or defective:

  1. Use the shortest possible high-quality network cable to connect the FRITZ!Box's power adapter to the FRITZ!Box, for example one of the two network cables included with delivery.
  2. Use the shortest possible high-quality network cable to connect the device to the LAN port on the FRITZ!Box's power adapter, for example one of the two network cables included with delivery.

    Note:Any standard network cable CAT 5e or higher (STP, 1:1) with a maximum length of 100 m is suitable for use with the FRITZ!Box.

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