I used the latest version of Wireshark to analyze the DHCP Discover process on the WAN port of the 1.0.2 and 1.0.4 code. I have found that under 1.0.2 code the DIR-655 sends out the DHCP Discover and gets the DHCP offer from the SB5120, then the DIR-655 sends out a DHCP request and receives a DHCP ACK.
Under the 1.0.4 code the DIR-655 sends out a DHCP Discover and gets a the DHCP offer from the SB5120, then the DIR-655 does not send out a DHCP request, it send a another DHCP Discover, the SB5120 sends out a DHCP offer, there is never a DHCP request from the DIR-655, which would lead to a DHCP ACK from the SB5120.
I have the capture files available to D-Links Tech support if you want them.
Vic