Panasonic KX-HN6002 Hub's Telephone Features and Power Failures

When setting up a hub for a smart home system, the manual recommends connecting the AC adaptor to a vertically oriented or floor-mounted AC outlet and not to a ceiling-mounted one. Why is this important, and what issues might arise if you connect it to a ceiling-mounted outlet? Additionally, can you explain the steps involved in configuring the hub to connect to a wireless router and registering a mobile device using the [Home Network] app? I tried to follow the recommendation from this link but it didn’t work https://mans.io/files/viewer/65599/11

If it is powered by a wall wart, I suspect they mean it is more likely to simply fall out of the outlet by gravity. A vertically mounted outlet would place the wall wart prongs at right angles to the force of gravity–and shear strength of the plug’s prongs would (generally) keep it from falling out.

It would be a YMMV situation if a ceiling mount outlet is used, depending upon the grip the outlet has on the prongs of the power supply!