Poor device (relative to each other) locations can lead to early WiFi failures .
The poorer the signal (bars) at the device, the more power the router needs to put out.
Best: is open field (line of sight from router Antenna to device)
Walls, plants, furniture in that direct path all add to signal reduction, forcing the router (and device) to try and over power those impeding objects.
General rule of thumb is to place the Router High and near the center of the Usage area (maintains the shortest cleanest path distance to all common usage locations)