FRITZ!Box 4020 Service - Knowledge Base
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, follow the instructions in this guide.
Simply proceed as described below. After each measure, check whether the issue persists.
1 Restarting the FRITZ!Box
- Unplug your FRITZ!Box by removing the power cable from the electrical outlet.
- Plug it in again after 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 supply unit
One of the most frequent causes is the use of an unsuitable power supply unit for the FRITZ!Box. For example, you may be using the power supply unit from a different FRITZ!Box model:
- Use the power supply unit included with your FRITZ!Box to plug it in.
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 that require more than 500 mA of current, 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:
- Remove all USB devices from the FRITZ!Box.
- For a sufficient period of time, observe whether the issue reoccurs.
- Connect the other USB devices one by one; only connect one USB device at a time.
- Check which USB device causes the issue to occur again.
- Connect this USB 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 may not exceed 500 mA. 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).
- For testing purposes, replace this device if the issue also occurs when using it with an active hub.
4 Resetting the FRITZ!Box
- Use the recovery tool to reset the FRITZ!Box.