To change the wireless settings of the router, you will need to open the set up page of the router. Do you have any computer connected to the router ? If not then you will need to connect a computer to the router and open the set up page of the router. Under the wireless tab you will find the wireless settings of the router. Chnage the wireless channel on mode and save the settings.
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Login to the router page.., you would be able to make the necessary changes under the section wireless in a linksys router.