Got a set of 3x deco e4 for my home. I'm using virgin media broadband, linked my virgin media router to the 3x units and havnt been best pleased with the performance. 
I've had the based regularly disconnect and show the red light. Sometimes needs power cable unplugged to reboot them, other times it resets itself. 
I've done a speed test on my original router and on the Deco units and seems to be a massive difference. But why? 
The reason I got the deco units was to expand the wifi, I'm using wifi security cameras on the property and need more range. But the weak/slower performance is affecting the recording of the cctv. 
I've taken a screw shot of the speed test to show the different.