@TP-Link also I have tried restarting all of the client devices themselves, modem and X20 devices - no change still could not connect to Internet.

@TP-Link The client devices are connecting to the Deco's themselves - the Deco's however are not letting the client devices see the Internet. The error message is essentially "No internet connection"...

@TP-Link can you please advise what to do here?

My Deco X20's have been working with around 31 devices connected mostly smart lights, Echo devices etc. various phones, tablets, laptops, 2 Apple TV's, 3 Amazon Fire TV sticks, 2 XBOX Ones. However,...