You cannot use the Toniebox with 5 Ghz networks.  

The majority of routers offer the possibility to activate the 5 GHz and 2.4 GHz frequencies simultaneously.

To find out if you have a dual-band router, check the manufacturer's website or your router's manual. If you got the router directly from your service provider, the customer service will know what to do.

If you do not have a dual-band router and still want to connect the Toniebox to your Wi-Fi, you will need to change the frequency band to 2.4 GHz. Please note that if you change this setting, you will need to reconnect other devices in your household to the Wi-Fi.