I was dismayed to learn that the DIR-890L completely lacks the capability to do MAC filtering. Yes, I know that spoofing MAC addresses is pretty trivial, and that the backbone of security is WPA2 with a strong password - but for a home, at $300 this is a pretty high-end router. It seems incredible to me that a relatively high-end router would lack very basic functionality that is present on just about every cheap model I've ever examined. It's probably not a critical thing, but I'd probably have kept on looking if I'd realized the DIR-890L lacked this feature.