D-Link AC1200 User Manual page 102

Section 4 - Configuration
Private Network Settings
Private IP: Specify the IP address on your local network to which the rule will
forward.
Private Port (start/ Specify a start and an end port to which the rule will apply. If you wish
end):
to specify a single port, specify a start port only.
Click Apply when you are done.
D-Link DIR-1210 User Manual 98