FRITZ!Box 6840 LTE – Service - Knowledge Base

FRITZ!Box 6840 LTE – Service

FRITZ!Box reports "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 300 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.

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 issue persists.

1 Enabling or refreshing the auto channel

If the auto channel is enabled, the FRITZ!Box checks the wireless environment and automatically selects the optimum wireless channel settings. However, the allocation of the frequency bands can change significantly over the course of the day. The FRITZ!Box does not refresh the auto channel as long as wireless devices are still connected with it. You can therefore manually refresh the auto channel at any time:

Note:All wireless connections to the FRITZ!Box are cleared and then automatically re-established when you enable or refresh the auto channel.

  1. Click "Wireless" ("WLAN") in the FRITZ!Box user interface.
  2. Click "Radio Channel" in the "Wireless" ("WLAN") menu.
  3. Enable the option "Set radio channel settings automatically (recommended)".
  4. Click "Apply" to save the settings.
  5. Click the "Refresh Auto Channel" button.

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.