Справочник Пользователя для ASUS RTAC66U

NAT Passthrough allows a Virtual Private Network (VPN) 

connection to pass through the router to the network clients. 

PPTP Passthrough, L2TP Passthrough, IPsec Passthrough and RTSP 

Passthrough are enabled by default.
To enable / disable the NAT Passthrough settings, go to the 

Advanced Settings > WAN > NAT Passthrough tab. When done, 

click Apply.