what exactly are you trying to do? Are you looking to expand or extend the signal of your wireless router?
if you're trying to expand or extend your signal, you would need to connect the 655 to 604 via lan to lan connection and NOT wan connection. make sure the ip settings are correct, 192.168.0.1 and the other router can be 192.168.0.2. The ssid can be set differently, dlink, and dlink-2. On the 604 disable the dhcp. Now you can either hardwire the lan connection or use a powerline adapter if hardwiring is not possible. I hope this is what you were looking for. Good luck.