@TP-Link The statements on web pages about Deco e.g. E4 are not fully true :

"Deco uses a system of units to achieve seamless whole-home Wi-Fi coverage — eliminate weak signal areas once and for all!" 

"A Deco E4 two-pack delivers Wi-Fi to an area of up to 2,800 square feet (EU version). And if that’s not enough, simply add more Decos to the network anytime to increase coverage." 

"Deco E4 provides fast and stable connections with speeds of up to 1167 Mbps and works with major internet service provider (ISP) and modem"

"Deco can handle traffic from even the busiest of networks, providing lag-free connections for up to 100 devices "

I have spent tens of hours to get 4 Decos E4 connected on wired backbone to work in a house made from bricks and wood. I have exchanged plenty of messages with TP-Link technical support. All that to setup wireless network for 1 PC, 3 laptops, 5 IoT 2,4 GHz devices with Vodafone high speed internet line.

The result was the IoT devices cannot connect each other, latency unacceptable grows and internet connection speed falls down when the distance of a client is more than 5 meters.

Finally I put back 2 prehistoric Ubiquity Unifi dishes and everything works fine.

During this exercise I have found that Deco works fine if you have Deco unit on the table where you work with your laptop. Also connection for your mobile phone or moving laptop in the same room could be acceptable. 

So there was total misunderstanding of Deco target business and deployment. It is suitable just for PCs and mobiles with Deco unit within a room to get connected with internet. And for such application the Web UI is not a must.

  @TP-Link Web UI is seems like a standard request. Using a phone is ok for basic needs...  but when you need to manage a device, a computer screen is the way to go

@DoinitSideways yeah I envy you, that was my setup until recently.

I have switched to cable and as such ISP supplied router. Having mesh is ideal to abstract away from changes in router but my gosh it's been super painful.