To be able to use the new 6 GHz band, the band must be activated on the WLAN-Box 3. To check this, visit the WLAN tab on the Web portal, which will show you whether or not you have WLAN or the 6 GHz band activated. The device to which the WLAN-Box 3 is connected must also support 6 GHz. These devices have the latest WLAN standard (WiFi 6E).
If you are using two WLAN-Box 3s, you can connect these to one another in a WLAN mesh network over the 6 GHz band. The resulting reduction in capacity usage of the 2.4 and 5 GHz bands also benefits devices that do not support the Wi-Fi 6E standard.