I think folks are a bit too picky about this issue.
Both my Galaxy S5s, and my Note 4s ( two of them ), all drop the WiFi and then log right back in.
You must keep in mind that they are working at a very high frequency, 2.x gHz and the slightest thing that intrudes into the path of the signal will cause problems. At those frequencies, signals bounce around and you have what is called "Multi-Path" reception.
That is where the signal is transmitted from an antenna and where you are, you can hear it from 2 or more different directions.
One path may be "direct in a straight line",
one path may be a bounce or reflection from the water tower behind you,
another path maybe a bounce/reflection from the mirror on the wall next to you ( yes, the silver backing on that mirror is a reflector to radio signals just like it is to light waves)
Another path may be filtering down to you through a tunnel and bouncing all over the place.
now, it only takes a little bit of "something" to change the strength of one of those signals for it to become stronger and over-ride the one the receiver was locked onto.... a nice windy day swing the limbs on that tree over your head.... yes, the trees contain moisture in their limbs and leaves, and they will block the signals.
Or, all you need is for someone to get up and start walking around, and the signal you were locked onto disappears for a 1/2 second.... then the receiver locks onto the next strongest signal, or lacking that, it locks back onto the signal that it lost as soon as it reappears and is strong enough....
This arena is where I have worked my whole entire adult working life, and no matter how much I explain to a customer "why his damn telephone, or short wave radio" isn't "worth the powder to blow it to hell" ( his words, not mine )..... it don't matter to the customer why the telephone connection got lost..... it is "all my fault for selling him junk"...
You can't win trying to fight someone's attitude. All you can do is try to explain that it ain't perfect, and it never will be.
Bottom Line: quit worrying about it.
As long as it locks back in, be happy it works.