FRITZ!Box 4040 Service - Knowledge Base

FRITZ!Box 4040 Service

Constant restarts: Several LEDs flash

The FRITZ!Box constantly restarts. When this happens, all or several LEDs either flash briefly several times or continuously one after another. Since the FRITZ!Box keeps restarting, you cannot access its user interface. Either particular functions or all of the FRITZ!Box functions are not working properly.

Important:If the FRITZ!Box occasionally restarts, proceed as described in this guide.

Simply proceed as described below. After each measure, check whether the issue persists.

1 Restarting the FRITZ!Box

  • Unplug the FRITZ!Box for 5 seconds.

    Note:The FRITZ!Box settings remain intact. The restart will take about 2 minutes. During this time, you cannot access the FRITZ!Box.

2 Using the correct power adapter

One of the most frequent causes is the use of an unsuitable power adapter for the FRITZ!Box. For example, you may be using the power adapter from a different FRITZ!Box model:

3 Disconnecting USB devices for testing purposes

Interference from USB devices connected to the FRITZ!Box may be causing the error. If this is the case, the USB devices may be defective, or the devices' system memory or file system may be damaged. USB devices connected to the USB 2.0 port that require more than 500 mA of current, or ones connected to the USB 3.0 port that require more than 900 mA, for example 2.5 inch hard drives or UMTS sticks, can also cause disturbances.
In order to test whether a USB device is causing the issue, proceed step by step as follows:

  1. Remove all USB devices from the FRITZ!Box.
  2. For a sufficient period of time, observe whether the issue reoccurs.
  3. Connect the other USB devices one by one; only connect one USB device at a time.
  4. Check which USB device causes the issue to occur again.
  5. Connect this device to the FRITZ!Box by means of a USB hub with its own power supply for testing purposes.

    According to the USB specifications, the power consumption of a USB device connected to the USB 2.0 port may not exceed 500 mA, and it may not exceed 900 mA for devices connected to the USB 3.0 port. If the device requires more than this, it must be connected to the FRITZ!Box by means of a USB hub with its own power supply (active USB hub).

  6. For testing purposes, replace this device if the issue also occurs when using it with an active hub.

4 Resetting the FRITZ!Box