In this example we will configure the Vigor2820 to only allow RDP access to a PC on the LAN from one IP address on the Internet.
Step1: Block all RDP access from the Internet
Go to Firewall>>Filter Setup and edit Filter set 2 rule 2
Select direction WAN ->WAN
Source IP: Any
Destination IP: Enter Any to block RDP to all devices or enter IP address if blocking access to a single PC.
Service Type: Enter TCP, Port from any to 3389. (We do not know the source incoming port that will be used).
Action: Block Immediately or Block if no Further Match.
Step2: Allow RDP access from the Internet to required PC