FRITZ!Box 7581 Service - Knowledge Base

FRITZ!Box 7581 Service
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Wireless or DECT connections are subject to interference when a USB 3.0 device is connected

A USB 3.0 device connected to the FRITZ!Box is causing disturbances to wireless (WiFi) or DECT connections to the FRITZ!Box. This greatly reduces the range of wireless or DECT connections.

1 USB 3.0 device is interfering with the wireless connection

USB 3.0 devices with insufficient shielding can interfere with the wireless connections of devices located very close to the USB 3.0 device or its USB 3.0 cable. Normally it is very rare for such interference to occur. When it does, it is usually only during data transmission via USB and with poorly insulated USB 3.0 cables that act like an antenna and amplify the USB 3.0 device's radiation.

The radiation from such USB 3.0 devices reduces the range and voice quality of DECT connections. In the case of wireless connections, the range and throughput of wireless devices connected to the 2.4 GHz frequency are reduced. Wireless connections in the 5 GHz frequency band are not affected by this.

This does not only occur with FRITZ!Boxes, it affects all wireless or DECT devices as a matter of principle.

Note:You can find additional information on this topic in this article in PCMag UK and this White Paper from Intel on the homepage of the USB Implementers Forum.


There are several ways to reduce the radiation affecting the FRITZ!Box. Start with the step that is easiest for you to implement:

  1. Increase the distance between the USB 3.0 device and the FRITZ!Box. If necessary, use a USB 3.0 extension cable to connect the USB 3.0 device to the FRITZ!Box instead of connecting it directly.
  2. Reposition the USB 3.0 device and its cable. Try connecting the USB 3.0 device to the other USB port on the FRITZ!Box, if it has one.
  3. Use a different USB 3.0 cable with better shielding.