Like Sgt K indicated, try setting the channel setting in the router's administration section to something other than "auto" or "ch 6". If you have an android phone or tablet, download/install/run the
WiFi Analyzer. It will show the in use channels in your area which will allow you to find the least used channel.
If you are using an older Wireless G router, some were affected when you use a microwave or certain wireless phones. I had an older Linksys router that would dump all wireless connections when I turned on a microwave. Also check other electronic devices, its possible you are getting interference from other electronics. If the router is next to a computer or other electronics, move it at least 2 or more feet away from all electronics.
It might also be advisable to use a new router that supports Wireless N if your wireless clients support it. I have all my wireless clients tied to a separate Wireless N router that is connected to my 2Wire AT&T modem/wireless router. I had nothing but trouble with the 2Wire wireless signal with some of my devices.