D-Link DWL-510 Owner's Manual page 9

Wireless Basics
3. Building Materials make a difference - a solid metal door or aluminum
studs may have a negative effect on range. Try to position wireless
devices, and computers with wireless adapters so that the signal passes
through drywall or open doorways and not other materials.
4. Keep your product away (at least 3-6 feet or 1-2 meters) from electrical
devices or appliances that generate RF noise.
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