Mijia Bedlamp 2 - wi-fi connection

Hi,
Mijia is a grat product but I really cannot link my phone with the lamp.
In particular, when Mi Home App is looking for Wi-fi connection, it say: “there is no available WI-fi connection”.
Yeelight App say the same, but even phone is connected with wi-fi to internet and it’s working.

My wi-fi router is set to free-wifi, SSID has a broadcast. Can be this a problem for the app? Do I need to have a WPA password protected wi-fi? If so, in one of the following update, can you remove this limit?

Thanks and best regards,
Floriano

The bulb can only work with a router using WPA/WPA2 encryption method with a password.

Thanks for prompt reply; I can understand. It would be aprreciated if in one of the following releases this limit can be removed by user.

This is the very last question: can it work only with a 2,4GHz wi-fi or can I connect to a 5GHz wifi?

Thanks again,

F.

2.4G only.