@jasongoldworthy, let's be precise. The WiFi symbol shows when you are connected to the router, and nothing else. When you are connected you get this icon:
And when not:
But all that is really showing is that the radio signals between the WiFi hotspot and the Mac are properly connected. You then have to have a successfully negotiated IP number assigned by the DHCP server, which you can see in System Preferences/Network under the appropriate interface. Finally, the router itself has to have a connection to the broadband bringing the signal to your home and an assigned IP from their server and lastly a true connection through them to a portal to the Internet. Lots of steps to get to the Internet and any or all of them could be the culprit when things don't work.
And the modernity of the device does not impact the success of the connection. WiFi signals don't work well through too many walls, floors, pieces of furniture, people, etc. And if there are several in proximity to one another (10 M) the signals can interfere, causing hot and cold spots. Fortunately, at the frequency of the WiFi, a matter of inches may solve the problem by moving the hot/cold spot. The OP has an iMac, which isn't really portable, but shifting it 6 inches to see if that improves the signal could be a solution. Or shifting the location of the router by the same amount.
And all routers typically have a range limit of about 10 meters. Some are slightly better, and you can always get a mesh router system to provide extra coverage, but the signals are kept to a low level to avoid interfering with neighbors. In an apartment block, you might be able to see dozens of routers because of the proximity. In my suburban environment, right now I see eleven, one of which is mine.