Going in Windows Task Manager > WiFi, i noticed i was connected using 802.11g despite both my laptop (Dell Inspiron 5547) and my Orange Livebox supports 802.11n.

I logged in 192.168.1.1. Tried to set the WiFi to 802.11n only.

But it wouldn’t allow me to.

I went on changing the encryption for my SSID.

And i got connected to WiFI 802.11n 😀