What wireless modes are you using on the host router?
Try single mode G or mixed G and N?
Channel Width set for Auto 20/40Mhz or try 20Mhz only.
Try setting a manual channel to a open or unused channel.
What security mode are you using? Preferred security is WPA-Personal. WPA2/AES Only. Some WiFi adapters don't support AES, so you might want to try TPIK only or Auto.
What wireless devices do you have connected?
Any other WiFi routers in the area? Use
InSSIDer to find out.
You could use AP mode and use the same SSID name, just make sure each DAP and host router are on different channels.