Need wifi booster/extender for Ruckus R610 Indoor Access Point

My Father-in-law has a Ruckus R610 Indoor Access Point. It was installed by his retirement community and he has no control over it. He lives in a cottage, and there is pretty good wifi coverage everywhere except in his bedroom. Ruckus does not recommend an extender - they say to eliminate interference, but I don't know of any interference they can eliminate. There is a fireplace and chimney between the AP and the bedroom. Any ideas for an extender I could buy for him to get better coverage in the bedroom?