I have the 3-pack of Deco X20s. Main Deco is connected via ethernet cable to the fiber optic unit coming into the house. The other two Deco units are connected via wifi. All Decos show green all the time. 

Fiber ----- ONT ---- Deco1  ----wifi---- Deco2 ----wifi---- Deco3

                                   |

                                   ------- 8 port switch ---- computer1

                                                                 |

                                                                 ---- computer2

Computers 1 and 2 are connected via ethernet cable to a switch, which is connected via ethernet cable to the main Deco. These computers almost never lose internet connection, so it's clear the internet connection is working to Deco1.

Wifi-connected phones, tablets, and laptops frequently lose internet connection, dozens of times per day. For instance, For instance, a laptop or phone web browser opens up a web page and works fine, then clicking on another link results in "no internet connection". Disconnecting from wifi and reconnecting SOMETIMES works but not always, and often it takes several disconnects/reconnects to make it work.

Wifi-connected smart TVs sometimes cannot connect, but once they do via disconnect/reconnect, the stream stays working as long as it's active.

Since you always ask the same questions, here are the answers:

1. All Decos show solid green all the time, even when a client loses internet. Deco app shows all clients (hardwired and wifi) connected.

2. ISP is Point Broadband fiber (formerly Intelliwave fiber), Deco is connected via ethernet cable to a Calix P Series 711 GE ONT (optical network terminal).

3. Internet disconnects on wifi devices occur all the time, whether stationary in sight of a Deco unit or moving around.