Can't find Airport Extreme??

[Jedi5]

Bought and installed Extreme today and it was working fine at first.
Fast forward a few hours and now my iMac can't find the router.

On my iMac I have no internet nor can it find my router.

I log on to my MBP, I have internet and the MBP can see the router.

Both are connected wirelessly yet only one has access to internet.

The router is located right next to my iMac so I know distance is not the problem.

Thoughts?

 

[Jedi5]

I've reset my router now at least 3 times.
Each and every time, I get the same thing.
iMac no internet and can't find Extreme while MPB has internet and sees Extreme.

Help?