Go to Advanced->NAT->Port Trigger page, you can configure the port trigger rules.
Nat Port rigger
enable or disable the port trigger function on the device
Application Type
you can select the service from the “Usual Application Name” or define the name from
“User-defined Application Name”
Start Match Port / End Match port
the start and end port to match
Trigger Protocol
the protocol to trigger the rule, it can be TCP, UDP or TCP/UDP
Start Relate Port / End Relate Port
the start and end relate port