@ImtiazAli 

In the app it was saying wifi was on and working, but I had zero wifi devices in connected clients. 

I used a wifi scanning app, there definitely was no wifi signal (I could see hidden wifi networks/etc, couldn't see the Decos one)

IoT network would show up if I turn it on, but it wouldn't let me connect

My second Deco also couldnt connect to the first/main unit (and the app said so also), like the wireless backhaul was missing.

I managed to get it all working again but factory resetting everything (major pain tbh.....)

But that said, my TV and a few other devices just keep connecting/disconnecting from the Deco now over and over, which makes streaming impossible 

Seems to have all happened after the recent update too, wonder if it's some kind of unstableness on the new firmware....