Mac Book Pro 2011 Messages Not Working

I have a fall 2011 MacBook Pro, and its been a few months and i cannot log into my Messages on my mac. My iPhone works fine, and i have changed passwords multiple times. I have tried changing my iCloud prefrences, but i cannot seem to get it to log in. Instead every time i try i get a message that says "Could not sign in. Please check your network connection and try again." and yet my internet connection is fine. This is very frustrating and would seriously like someone to give me a fix or recommend what to do, as I've tried everything apple has recommended.

HALP!