Comparing Port Forwarding and Port Triggering
These features allow some internet users to have access to specific resources on your network, while protecting the resources that you want to keep private. Some examples of when this is used: hosting web/email servers, alarm system and security cameras (to send the video back to an offsite computer). Port forwarding opens ports in response to inbound traffic for a specified service.
A list of these ports and their description are set up when you enter the information in the Service Management section of the set up wizard. When you set these up, you cannot use the same port number for both port forwarding and port triggering.
Port Forwarding
Port forwarding is a technology that allows public access to services on network devices on the Local Area Network (LAN) by opening a specific port for a service in response to inbound traffic. This ensures that the packets have a clear path to the intended destination, which allows for faster download speeds and lower latency. This is set for a single computer on your network. You need to add the specific computer's IP address and it cannot change.
This is a static operation that opens a specific range of ports that you select and doesn't change. This may increase security risk as the configured ports are always open.
Imagine that a door is always open on that port to that device that it was assigned.
Port Triggering
Port triggering is similar to port forwarding but a little more secure. The difference is that the trigger port is not always open for that specific traffic. After a resource on your LAN sends outbound traffic through a trigger port, the router listens for inbound traffic through a specified port or port range. Triggered ports are closed when there is no activity, which adds to the security. Another benefit is that more than one computer on your network can access this port at different times. Therefore, you do not need to know the IP address of the computer that will trigger it in advance, it does this automatically.
Think of you giving someone a pass but there is a doorman there that checks your pass each time you enter and then closes the door until the next person with a pass arrives.
https://www.cisco.com/c/en/us/support/docs/smb/routers/cisco-rv-series-small-business-routers/smb5818-configure-port-forwarding-port-triggering-nat-on-rv34x-serie.html
