[idi banashapan]

START > Control Panel > Network and Sharing Centre > Manage Network Connections (on the left) > Right click on your wireless connection and select Properties > click Advanced > in there will be a setting for the channel your wifi device is using - ensure it is set to the same as your router. some can auto-determine, but set it munually if you can.

to find what channel the router is using, you will either need to check the manual or take a look on the admin console (usually http / https)