In your situation, your ADSL router is providing a private ip address
to your wireless router, its not passing the public ip address along as
some DSL & Cable modems do. For that reason, you've essentially got two
firewalls. You'd have to open up port 5900/5901, 5800/5801 (all the vnc
ports) on both the ADSL router AND the D-Link router.
My suggestion would be to cut this down to one firewall. The easiest
way to do this with the same hardware is to configure the DMZ on the
ADSL router to point to your D-Link router and have the D-Link act as
the firewall to the network. Statically configure your ip address on
the D-Link router so that it always uses the same ip address to talk to
the ADSL router, then configure the ADSL router's DMZ setting with that
ip address. This will open all public ports to the D-Link router. Then
on the D-Link router, create an address reservation for your client pc
that's running as a vnc server, and go to the port forwarding section.
Configure the ports I mentioned above to forward to that pc's reserved
address. Creating a reservation allows the pc to still grab its
configuration automatically, but ensures that it will always have the
same ip address; essentially a static address.
If you dont want to open the DMZ on the ASDL router or if the ADSL
router does not have a DMZ, just open the same ports on the ADSL router
and point them to the ip address of the D-Link router on the outside
interface. You will still need to configure port forwarding for the
client as described above.
