rb951g-2hnd mounting

Just picked up one of the rb951g-2hnd units and would like to know a good recommendation for mounting it. Ideally, I’d like to mount the unit up in my attic at the crown point, which is around 16-18ft high. If I do that, would the wifi throw pattern be ok? Or does it need to be mounted lower?

Also, is it better to mount the unit on it’s side against a wall or laying flat, like on a ceiling? Thanks guys.

baggar11