If that question was directed to me, then yes, the "Disable Gateway Smart Packet Detection" box should be checked (as you have it).
That so called "Smart Packet Detection" is in theory an anti DoS function, but my own testing revealed that it caused internal DoS problems itself by mistaking normal traffic as an attack and blocking traffic inside the router. It seemed to especially not like VPN and SIP/RTP traffic.
One of the symptoms I saw whenever that box was not checked was random disabling of the html admin interface. -- We can never have enough of nature. We need to witness our own limits transgressed, and some life pasturing freely where we never wander.