Frustrating Wi-Fi issues

I am having this wifi connectivity problems at work only. Last week they changed the modem, all the pc computers in the office work fine after that, before that my internet on my macbook pro was working excellent.
Here is the deal:

My airport detects the wifi and says it is connected, but not one browser I have is working, so internet is down for me. I have been on several forums and many people goin through the same problem, but they resolved their issue with following solutions that are not working for me, and I have run out of options.

Here are solutions that didn't work for me:

-Go to system preferences
On the top row click on security
Click on firewall
Highlight - Allow all incoming connections

-deleting and re-introducing Airport into your network settings.

-dns settings

-deselecting proxies

-deleting network configurations and rebooting.

any ideas?

 

got it working, thank you!