I have a problem with my internet connection. I've been connected to the same wifi for almost 2 months and never had any problems until a few days ago. I turned my MacBook Air on and there was an exclamation symbol on the wifi symbol. When I go to "system preferences" > "network" it says under wifi that there's no IP address. I've been on lots of forums, tried to restart the laptop etc but nothing seems to be working. Any ideas ??