In my experience location is a big deal with wireless gear. If the grill was metal then that could cause problems. It was listed as mistake #1 in something I recently read in the blog listed below. Here's the relevant passage:
"Mistake 1
• Access points with integrated omni-directional antennas (where the max gain is sideways) are placed among or above metal air ducts, grids and large lamp reflectors.
• Outcome: A lot of reflections and refractions cause multiple copies of the signal to arrive at receivers, thereby dropping the data rates. As the radio waves reflect in random directions, the signal strength suffers at both ends."
http://7signal.com/blog/10-wi-fi-antenna-placement-mistakes/
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