Half Bridge mode is your friend here.
Not sure if the D-Link supports this mode however, Google is less than
helpful. Essentially in half bridge mode the modem handles the PPPoA
authentication with the ISP, as in NAT mode obtaining an IP address from
the remote provider as normal. Unlike NAT mode however the modem then
leases out this exact same IP address to the connected ethernet host,
thereby presenting the external IP directly to your external ethernet
port. Finally the modem begins to transparently bridge the ADSL/Ethernet
connections.
I can vouch for Zoom X3/4 and ADSL Nation X-Modems working in this mode
without issue.