Why doesn't dropbox always upload info?

Question

dropbox

there are two productions. The exchange of information takes place through dropbox (1 production => dropbox => 2 production) infa is loaded in 1s. But it happens that infa comes immediately, after a while or does not come at all. Maybe it's not at all on the side of production 2 (I'm on the side of production 2)?
the main router MikroTik Router RB750Gr3
local network gigabit
fiber was specially led to production 2 we are the only ones sitting on it, through the lan port from 99-120 the speed in the internet, wifi is average from the laptop 80
and at such a moment the employees said that this happened Thursday Friday, since these days, basically, all the movements begin. And now they raise a riot on other days.