WiFi is not working.

There are a couple of possibilities...

• Your systems WiFi (AirPort Extreme) is only 802.11g/n, so if you have a 802.11ac access point (AP) on your Router it maybe set to only advertise 802.11ac connections.
• Your Routers AP name broadcast maybe turned off. Many people to day turn it off once they have set it up.
• Your Routers AP may be configured for only WAP/WAP2 encrypted connections (which is a good thing!)
• You also maybe in a dead zone within your home or apartment and/or there is too much signal noise from other nearby WiFi systems (a common issue in the cities now)

And lastly you could have a hardware issue as well!

Lets see if we can double check things. Click on the WiFi symbol on your menu bar but also hold the Option key this will show you the adapter, drivers and any discovered AP's. Take a screenshot pressing the Command & Shift keys paste the menu pull down in your question so we can see what it shows us.