TP-Link Pharos Series User Manual page 80

Port Trigger Enable or disable port trigger. Due to the existence of the firewall, some
applications such as online games, video conferences, VoIPs and P2P
downloads need the device to configure the forwarding to work properly,
and these applications require multiple ports connection, for single-port
virtual server cannot meet the demand. Port trigger function comes at this
time. When an application initiates a connection to the trigger port, all the
incoming ports will open for subsequent connections.
To configure port trigger:
Click Add , specify the following parameters and Enable the entry. Click
Save .
Enter the incoming port for incoming traffic. The port or
port range is used by the remote system when it responds to the outgoing
request. A response to one of these ports will be forwarded to the PC that
triggered this rule. You can input at most 5 groups of ports (or port section).
Every group of ports must be set apart with ",". For example, 2000-2038,
2050-2051, 2085, 3010-3030.
Enter the trigger port for outgoing traffic. An outgoing
connection using this port will "Trigger" this rule.
Choose the one of the protocols used for this application: TCP,
UDP, or TCP/UDP.
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