FRITZ!Box 3370 – Service - Knowledge Base

FRITZ!Box 3370 – Service

Error message "Wireless LAN transmission quality increased by reduced channel bandwidth [...]"

Wireless connections (WiFi) according to wireless standard 802.11n are established with a throughput that is considerably less than 450 Mbit/s. In this case, the error message "Wireless LAN transmission quality increased by reduced channel bandwidth [...]" is displayed in the event log of the FRITZ!Box.

Cause

  • The FRITZ!Box recognizes that the wireless channels it uses in the 2.4 GHz frequency band are subject to heavy use by other wireless networks. In order to still guarantee stable wireless connections, the FRITZ!Box automatically reduces the channel bandwidth to 20 MHz. Although the wireless devices display a lower throughput as a result, the user throughput is higher because it is not affected by retransmissions. This FRITZ!Box function ("wireless coexistence") complies with wireless standard IEEE 802.11n.

Important:Some of the settings described here are only displayed if the advanced view is enabled in the user interface. The configuration procedure and notes on functions given in this guide refer to the latest FRITZ!OS

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

1 Selecting the best wireless channel

By default, the FRITZ!Box checks the wireless environment automatically. However, with some disturbances it cannot determine the best wireless channel for all of the wireless device. Therefore, select the wireless channel in the FRITZ!Box that is least affected by disturbances in the wireless environment:

  1. Click "Wireless" ("WLAN") in the FRITZ!Box user interface.
  2. Click "Radio Channel" in the "Wireless" ("WLAN") menu.
  3. Use the graph "Use of the Wireless LAN Channels" to determine which channel in the lower frequency range is least affected by other wireless networks and sources of interference.
  4. Enable the option "Adjust radio channel settings" in the "Radio Channel Settings" section.
  5. Select the wireless channel that was affected the least from the drop-down list "Radio channel".
  6. Click "Apply" to save your settings.
  7. Check whether the issue with your wireless connection still occurs.
    • If the issue with the 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.

2 Establishing a wireless connection to the 5 GHz frequency band

The FRITZ!Box either provides a wireless network in the 2.4 GHz or the 5 GHz frequency band. The 5 GHz frequency band is subject to interference less frequently. 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. Click "Additional Settings".
  5. Select the standard "802.11n+a" from the "Wireless standard" drop-down list.
  6. Click "Apply" to save your settings.
  7. Re-establish the wireless connection to the FRITZ!Box.

The FRITZ!Box now establishes wireless connections with the highest possible throughput.

Note:If the error message "Wireless LAN transmission quality increased by reduced channel bandwidth [...]" is still displayed in the event log of the FRITZ!Box, then this is because of the heavy use by wireless networks in the vicinity.