After a restart or changes to the Wi-Fi settings, at first the FRITZ!Box only enables the 2.4 GHz Wi-Fi network. FRITZ!Box does not enable the 5 GHz Wi-Fi network until after completing the check for higher-priority users (DFS wait time), such as radar systems for the weather service, which can take up to 10 minutes. The FRITZ!Box must always comply with the DFS wait time regardless of the Wi-Fi channel that is set, because even on Wi-Fi channels 36 to 48, part of the frequencies required by the FRITZ!Box for 160 MHz channel bandwidth are in the DFS range (channel 52 - 140).

Even during operation, the FRITZ!Box continuously checks whether the Wi-Fi channels being used are still unused by higher-priority users. If the FRITZ!Box detects one of these users, it disables the 5 GHz Wi-Fi network, searches again for higher-priority users for up to 10 minutes, and then re-enables the 5 GHz Wi-Fi network on a different Wi-Fi channel not used by them.

Only FRITZ!Box models with Zero Wait DFS (for example FRITZ!Box 7590, FRITZ!Box 6591 Cable) can avoid the DFS wait time. After a restart or a change to the Wi-Fi settings, FRITZ!Box models with Zero Wait DFS initially only enable Wi-Fi channels 36 to 48 of the 5 GHz Wi-Fi network and at the same time check the DFS range for higher-priority users. Afterwards, these FRITZ!Box models switch to higher channels and 160 MHz channel bandwidth.

Important:If you use the same Wi-Fi network name (SSID) for the 2.4 and 5 GHz Wi-Fi networks, your wireless devices will automatically connect to the 2.4 GHz Wi-Fi network during the DFS wait time. For this, configure the FRITZ!Box as described in the guide Optimizing the Wi-Fi network of the FRITZ!Box.