[Raistlin]

Wireless routers typically operate across a number of frequencies, usually allocated across channels numbered 1 to 11 (sometimes 1 to 13).

Your router will have been set up to operate on a default channel by the manufacturer, and probably hasn't been changed since.
If someone else near you has a router operating on the same channel, or on one near to it, you will get interference from their router and will experience loss of signal every now and then.

Look at the instructions for your router, there should be some sort of administrative interface (usually the bit where you set up the security options etc) which should allow you to change the channel that the router is operating on.

Try the available channels one at a time, leaving each for a day or so in order that you can see how it's working, and see which gives the best results.

You may need to reboot the router and/or other wireless devices when you change channel to ensure that they have all changed to match the channel on the router.