[lubuntu] weird wireless problem

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http://ubuntuforums.org – Hi.I have a USB wireless adapter TL-WN422G.It works fine in Lubuntu and i can connect to my router but this is true only when i am near the router.when i get far from it,lubuntu fails to find the router.On the other hand in windows xp the adapter connects fine when i am far away. Please help.What problem is this:mad: (Hardware)