DIAGNOSIS The one-click "Prioritize Gaming" toggle is mostly for QoS (Quality of Service). For actual open ports (port forwarding), you need to use the web interface, not the app. The app's features are limited.
FIX Log into the router's web interface at http://linksyssmartwifi.com. Go to Connectivity > Advanced Router Settings. Click on the "Single Port Forwarding" tab. Here, enter the application name (e.g., "Xbox Live"), the external and internal port range (like 3074 for both start and end), the protocol (TCP/UDP or Both), and most importantly, the IP address of your gaming console or PC. You need to assign that device a static IP first, which you can do under the "DHCP Reservation" tab on the same page.
IF THAT DIDN'T WORK Some games/services use a range of ports. You may need to set up multiple entries. For consoles, you often need to forward ports 3074 (TCP/UDP), 3544 (UDP), and 4500 (UDP). Check your game/console's support site for the exact ports.
HEADS UP Port forwarding is a security trade-off—you're poking a hole in your firewall for that specific device. Make sure the device you're forwarding to has a strong password and updated software. Also, your ISP might block certain ports on their end, which the router can't fix.