NAT issues despite address reservation in DumaOS on NETGEAR Nighthawk Support Posted October 15, 2018 5 hours ago, Netduma Fraser said: Great to hear that resolved the issue! NAT Filtering: This option determines how the router deals with inbound traffic. The Secured option provides a secured firewall to protect the PCs on LAN from attacks from the Internet, but it may cause some Internet games, point-to-point applications, or multimedia applications not to work. The Open option, on the other hand, provides a much less secured firewall, while it allows almost all Internet applications to work. Well two people on Reddit were praising this option up and down, saying how it was literally all they ever had to do. I was inclined to think security wise it was probably a bit more vulnerable but maybe I will give it a try if I ever encounter a problem.