The thing I liked about the D6400 was it covered the whole house with wi-fi and I didn't have to use a range extender for devices upstairs.
Sadly the 3490 doesn't and so I've had to put in a range extender which means another device I have to keep an eye on.
The Blue Cave looks as though it might do what I want but I wondered if anyone knows if it works ok with Zen's standards based implementation of IPv6?
Router: Fritzbox 3490
Note: I don't lay turf for anyone. astro or otherwise, all views and opinions expressed are my own based on experience.