D-Link DAP-1620 Manual page 13

Step 9: Unplug and place the range extender approx half way between the router
and the desired connection area.
Note: Correct placement of the range extender is very important. It needs to be
positioned in an area that still receives good signal from your router. A good
starting point is approx half way between the router and the area you want to get
signal to.