ROOTED DEVICES ONLY
Turning WiFi Off, clearing DCHP information, then turning WiFi back ON.
1. Turn OFF Wi-FI.
2. With your favourite file manager (Root Explorer 🙂 ) deleting all files on the next path /data/misc/dhcp
3. Reboot your device, turn ON back WI-FI and just type password of your wireless network.
ENJOY ¡¡ 🙂