my computer loses wifi connection using an airport extreme
I have an airport extreme and both of my computers, a macBook air and and iMac are constantly losing wifi connection. I have upgraded the firmware as my airport utility said to do, and green light is on on the airport extreme......what else can I do to fix this problem. The airport extreme is 3-4 years old, is that the normal life span???
AirPort Extreme 802.11n (5th Gen), OS X Yosemite (10.10.2)