router antenna direction

I have a new router with 3 antenna, set-up as below.


My router is in the middle of the top floor, and I have 2 floor below.

Conventional wisdom say put it like 3 finger sticking upward, but i am not sure if it the best way for my scenario.

 

These routers are meant to provide coverage on the same level as they are located. In such a case pointing the all upwards will work best.

If you orient them horizontally it would improve reception below (and above if there was anything above) to a degree (somewhat limited by floor/celling obstacles) but at the same time would make the reception atrocious on the level where router is located.

With omnidirectional antennas the signal look like a donut with an antenna in the middle of it- so reception above and below (and especially directly above and below) is not very good.

You could possibly leave the middle one vertical and set remaining one or two at outwards angles so these two would cover the floor below.
While it might improve reception one floor below it will probably decrease throughput on the floor where router is located too.

Middle floor instead of the top one would be better as well.

And the best solution- at least two devices (bottom and top floor if two), the second one being an AP fed with Ethernet cable.

 

Tinkered a bit with it, the iffy spot(a corner in the basement) remain iffy, just sticking in a repeater for now.