Have anything on the same frequency? Cordless phones?
Tried changing the channel?
Router have the latest firmware? (Answer should be yes)
Set security to WPA? (Answer should be yes)
Broadcasting SSID? (Answer should be yes)
Reboot the router?
I have a linksys wireless router, which was working fine up until a few days ago. The lights are still on, but internet access cuts off fairly often. Sometimes the network does not show up on our computers at all, and even when computers are plugged into the ethernet port, we can't get to the internet. Our internet/cable provider says the signal to our house is fine. Does the router need to be replaced or is this something that resetting it would fix?