i cant connect my wireles livebox to my laptop

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i hav an orange livebox. i have my playstation 3 and my laptop linked wireless to the livebox.Yet for some reason when i got my laptop my sisters laptop stopped workin and i cant connect my iphone to the connection either.I looked online to see how many wireless devices it holds and it says about 6 after tht the connection gets weaker or something.Please could someone help me connect this laptop and iphone ? thnxx