* What power is the IAP-275 running at?
* Is it on the same cluster as other IAPs or is it standalone?
* Is the LED on and if so what color/status (solid, blinking, etc)?
Connectivity between the 275 and a client can stretch to 200-300m outdoors with clear line of sight and no obstructions between the AP and client. Indoors with walls, obstructions, people, etc that number could vary wildly and there's no way to project/estimate without better information (floor plans noting wall types, environment, etc, locations of AP and people, etc).