The AirPort menu bar icon

The AirPort menu bar icon on my MacBook Air shows that I have no internet connection, but I can connect to internet. It is not an huge issue, due to the fact that I can use the internet, it is just annoying. I have reinstalled OS, still no change.

This is happening all the time, we different routers. In my office we are using a dlink router, at home I have an airport express. I have tried it in different locations, still the same.

I would be gratful, for a solution.