D-Link DSL-6740U User Manual page 64

Section 3 - Configuration
ADD OUTBOUND IP FILTER
Click Add button to set outbound IP filter rule.
Enter the Filter name and at least one of the following criteria:
Protocol, Source/Destination IP Address and Subnet Mask, and
Source/Destination Port.
Click on the Apply button to apply settings.
D-Link DSL-6740U User Manual 64