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WEBUI
Step 1: Login to webui, from navigation -> Advanced ->Port TriggeringForwarding. Click on Add Port TriggerForwarding.
Testing Steps (TCP and UDP)
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Router configure Trigger port 443:443 and Target port 21:21.
From External network(WAN) try to access ftp server of client machine(LAN client) using router uplink ip address(Goto terminal enter ftp -p 192.168.2.30 in WAN client),
while client machine(LAN)run https service(In browser https://www.google.com)...