Thank you for the information. So I take that as 1+2+3 antenna chains in DD-WRT for both TX and RX. Does the "x2 for power" translate into a "2 dBi" antenna gain setting in DD-WRT?
Yes (drmemory)
Also, how is the internal PIFI antenna oriented? The external antennae can be oriented "upward" whether the device is standing or on its flat side. If I want the internal antenna oriented in the vertical direction (so as to radiate horizontally), should I stand the unit on edge (external antenna on top) or place it on its side? It has feet for both orientations.
The PIFI is vertical, when the WZR is upright. The WZR uses antenna diversity between the antennas - they search for the best signal, in case of multipath interference. (drmemory)
Thanks again for the clarification -- there is nothing in the documentation I could find about this.