D-Link JustConnect DNR-4020-16P User Manual page 51

Section 3 - Configuration
Port Number
On this page you can set the ports that the NVR will use to transfer data and allow
clients to connect to.
HTTP Port
The HTTP port for the web UI.
Data Port
The port that data will be transferred over. The port that client devices
will connect to.
Client Port
It is necessary to reboot the device after modifying any of the
port configuration settings.
D-Link DNR-4020-16P User Manual 46