FRITZ!Box 7340 Service - Knowledge Base

FRITZ!Box 7340 Service

FRITZ!Box reports "A microwave was detected"

The speed of the wireless connection (WiFi) to the FRITZ!Box displayed by wireless devices such as computers, smartphones, or tablets, is significantly lower than the data rate possible with the wireless standard 802.11n. The following message is displayed in the event log of the FRITZ!Box:

  • "Wireless LAN: a microwave was detected; radio channels optimized for 300 Mbit/s temporarily deactivated (2.4 GHz)."

Cause

  • The FRITZ!Box detects sources of interference, for example a microwave in the frequency range around 2.45 GHz. To ensure stable wireless connections, the FRITZ!Box automatically reduces the channel bandwidth from 40 MHz to 20 MHz. Although wireless devices then display a lower data rate, the user data rate is increased because there is less interference and the wireless connection is no longer affected by constant retransmissions.

Note:The configuration procedure and notes on functions given in this guide refer to the latest FRITZ!OS for your FRITZ!Box.

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

1 Identifying sources of interference

  1. Turn off all devices that could interfere with the wireless network.

    Note:All devices that emit radio waves are possible sources of interference. These include other wireless devices, wireless speakers, Bluetooth devices, baby monitors or microwaves, for example.

  2. Check whether the wireless connection is still impaired.
    • If the wireless connection is no longer impaired:
      1. Turn the devices back on, one after the other.
      2. Each time you turn on a device, check whether the wireless connection is impaired again.
        • If you identify a device or devices causing interference, you have the following options:
          • Leave the devices that cause interference turned off,
            • or:
          • Enable or refresh the auto channel (see the section "Enabling or refreshing the auto channel"),
            • or:
          • Find the ideal location for the FRITZ!Box (see the section "Finding the ideal location for wireless devices").

2 Finding the ideal location for the FRITZ!Box

  1. If possible, position the FRITZ!Box in a room that is centrally located.
  2. Do not position the FRITZ!Box directly in the corner of a room.
  3. Position the FRITZ!Box so that it is as unobstructed as possible, i.e. not directly in back of or under an obstacle such as pieces of furniture or a heater.
  4. Position the FRITZ!Box as high in the room as possible, for example on a shelf.
  5. Position the FRITZ!Box so that there are as few obstacles as possible between it and other wireless devices. In particular, metallic objects or objects containing water, for example radiators, refrigerators, or even houseplants, significantly reduce the quality of the wireless signal.
  6. Position the FRITZ!Box so that it is away from other transmitters, for example microwaves, wireless speakers, or Bluetooth devices.

3 Selecting the best wireless channel

  1. Click "Wireless" ("WLAN") in the FRITZ!Box user interface.
  2. Click "Radio Channel" in the "Wireless" ("WLAN") menu.
  3. Click the link "Show disturbances to wireless network" in the "Wireless Environment" section.
  4. Use the graph to determine which channel in the lower frequency range is least affected by other wireless networks and sources of interference.
  5. Enable the option "Adjust radio channel settings" in the "Radio Channel Settings" section.
  6. Select the wireless channel that was affected the least from the drop-down list "Radio channel".
  7. Click "Apply" to save the settings.
  8. If the issue with your wireless connection still occurs, repeat steps 3 - 7 with a wireless channel in the middle and then with one in the higher frequency range. Once you have finished testing, use the wireless channel that was least affected by disturbances.

    Important:The diagram of the wireless environment only reflects the current situation! The allocation of the frequency bands can change significantly over the course of the day because many wireless networks are turned on when in use. Therefore, check several times to see which wireless channels are least affected by interference.

4 Establishing a wireless connection to the 5 GHz frequency band

The FRITZ!Box either makes a wireless network available in the 2.4 GHz or the 5 GHz frequency band. The 5 GHz frequency band is not affected by interference as often. Therefore, switch to this frequency band if your wireless devices support the 5 GHz frequency band:

Note:Not all wireless devices support the 5 GHz frequency band.
FRITZ!WLAN Stick AC 430, FRITZ!WLAN Stick AC 860, and FRITZ!WLAN Stick N (v2) support the 5 GHz frequency band.

  1. Click "Wireless" ("WLAN") in the FRITZ!Box user interface.
  2. Click "Radio Channel" in the "Wireless" ("WLAN") menu.
  3. Enable the option "Adjust radio channel settings".
  4. Select the standard "802.11n+a" from the "Wireless standard" drop-down list.
  5. Click "Apply" to save the settings.
  6. Re-establish the wireless connection to the FRITZ!Box.