WN3000RP WiFi Range Extender does not provide Internet for smartphone

Hello all,

I have at home a WiFi network through a NETGEAR CG3100Dv3 Cable Gateway and a NETGEAR WN3000RP WiFi Range Extender, so I have actually 2 WiFi networks, one from each device.

Usually my smartphone can automatically connect to Internet through the WiFi supplied directly by the Cable Gateway. But very often it can not connect to Internet through the WiFi supplied by the Range Extender, so I cannot surf the Internet or use Whatsapp for example. And however my computer connects to Internet normally through that Range Extender.

Is it a failure of the Range Extender? Or is there a way to set it so that the smartphone (or other devices like tablets) can connect to Internet through it?

Waiting for someone's answer, thanks in advance.