Do you have the 655 set up as and AP or still running the 655 as a standard router off the host router?
Turning a router in to an APWhat wireless modes are you using? Under Setup/Wireless/Manual.
Try single mode G or mixed G and N?
Channel Width set for Auto 20/40Mhz or try 20Mhz only.
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.
Turn off Short GI and Extra Wireless Protection if you have it. Under Advanced/Advanced Wireless.