I seem to be having a similar but opposite problem with Fios, Orbi with 2 satellites, and an LG V10 phone. Orbi is set as an access point and everything has the same SSID. As soon as the signal strength falls even a little below -65, the LG drops out for 2 to 3 seconds and then finds its own way back to the strongest signal, which is usually the closest satellite. BUT this is just enough time to lose a phone call I'm in the middle of.
The Android app "Home Wifi Alert" provides good detail regarding signal strengths and a great deal more information about my network. Using this is how I was able to see exactly when/where the signal dropped and how totally sudden the drop is. I have found that if I "train" myself to race through the place where it drops, I'm likely to lose a few words but often can avoid dropping the call.
Of course, this is less than an "ideal" solution :)
After carefully positioning the Orbi satellites using "Home Wifi Alert" as described above, I added SWIFI as recommended here. Since Orbi does allow for a Guest Network as well as the one SSID it creates, I added a Guest Network. Then SWIFI had two networks to switch between. With careful adjustment of SWIFI, I am now able to roam my house and SWIFI switches between the main Orbi SSID and the Guest SSID. Although I'm notified that a network has been disconnected, the other network has already been connected and I have not lost a call since.