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LAN connection to FRITZ!Box cannot be established

The LAN port cannot be used to establish a connection to the FRITZ!Box. A computer, NAS system, or other network device connected to the FRITZ!Box is not detected and cannot access the internet or the FRITZ!Box user interface. One of the following error messages may be displayed by the device:

  • "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.

1 Restarting the FRITZ!Box

  1. Unplug the FRITZ!Box for 5 seconds.

    Note:The FRITZ!Box settings are retained when you unplug it. The restart takes about 2 minutes. During this time, you cannot access the FRITZ!Box.

2 Installing the latest FRITZ!OS

Perform the following steps on a different device connected to the FRITZ!Box:

Important:If you cannot access the FRITZ!Box with any device, proceed as described in the guide FRITZ!Box user interface cannot be opened.

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

3 Installing the latest software for network adapters

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

    Note:Since Windows Update often does not install the latest device drivers, install the drivers from the manufacturer's website (for example Intel, Broadcom, Realtek).

4 Connecting the device directly to the FRITZ!Box

This step is only necessary if the device is not directly connected to the FRITZ!Box, but through a hub/switch, powerline adapter, LAN/Wi-Fi converter, or other devices instead:

  1. Connect the device directly to a LAN port on the FRITZ!Box. If possible, use the yellow cable included with the FRITZ!Box.
  2. If you can establish a LAN connection to the FRITZ!Box now, 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. Use the shortest possible high-quality network cables (CAT-5e).

5 Testing a different cable

The device may be connected to the FRITZ!Box by means of a network cable that is too long, incorrectly wired, or defective:

  1. Use the shortest possible high-quality network cable to connect the device to the FRITZ!Box, for example use the network cable included with the FRITZ!Box.

    Note:Any standard STP-type (Shielded Twisted Pair, 1:1) CAT-5e Ethernet cable with a maximum length of 100 m can be used to connect a network device to the FRITZ!Box.

6 Connecting a 10BASE-T device using a cross cable

The following step is only necessary if the respective device is connected to the FRITZ!Box by means of a 10 Mbit/s (10BASE-T) network adapter:

  1. Use a cross cable or crossover network cable (network cable with twisted cable pairs) to a LAN port on the FRITZ!Box.

    Note:Many devices with 10BASE-T network adapters (for example measuring instruments, smart home devices, or internet of things devices) do not support auto MDI/MDI-X and therefore need cross cables. Cross cables can be purchased from electronics retailers.

7 Disabling energy-saving functions for the network adapter

  1. If 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.

8 Adjusting the FRITZ!Box's LAN settings

Problems may occur when negotiating transmission rates. Therefore, test whether the connection can be established when you adjust the settings for the LAN port being used:

  1. Open the FRITZ!Box user interface on a different device.
  2. Click "Network" in the "Home Network" menu.
  3. Click on the "Network Settings" tab.
  4. If "Green Mode" is enabled in the section "LAN Settings", enable "Power Mode".
    • If "Power Mode" is enabled, enable "Green Mode".
  5. Click "Apply" to save the settings.

9 Testing a different device

  1. Connect a different device to the LAN port on the FRITZ!Box.
  2. If the other device can access the FRITZ!Box and the internet, the first device is either incorrectly configured or defective.