Instructions basically say to forward Port 80 and Port 9000 to the IP address of your DVR, You might want to set a static IP because if its DHCP now and the router for some reason decides to give it another IP address then the port forward settings would not apply to the new IP. Also note what kind of modem you have as it is DSL then it might be doing some NAT on its own so basically you could be running NAT back to back so you would have to forward the ports on each device. Also and this applies if you do have a DSL modem that does NAT, just get a small switch and attach that to your modem, then the switch to your 615 and to the DVR, this way the DVR is only behind one NAT.
[modem] --> switch --> 615
|
-----> DVR