Wireless connections can be affected by many factors. Some router related and some not. First make sure you are on challen 1, 6, or 11. All others overlap. Then check for interference with other wireless LANs in your area. A free download such as "inSSIDer" will give you visibility to other networks. Also check your signal strength and positioning at the laptops. If the signal strength is low, make sure your 2wire signal output is as maximum (at least to test). Also, make sure the laptop is not surrounded by metal (e.g. on a wire shelf or cart), and that there is not some interference like next to a microwave.