Yes, but is your all-in-one server, also a DHCP server? You did not state this in your answer.
Remember, if you are using your DIR-615 as an AP, you are effectively converting it to a switch but using your wireless setup on the DIR-615 to make a connection through DIR-615 to the DHCP server. You would set a fixed ip address on your DIR-615 to be on the same network that your DHCP server. Also, disable DHCP on the DIR-615, so that it is just a pass through switch (also it avoid ip conflicts.)