@David-TP 

Hi, thank you for replying.

I have a gigabyt internet connection but the problem is that right now the E4 is working as the main router where the ethernet cable is plugged in, so that's why the speed is capped.

This is why I am trying to buy another primary routher and to use the E4 as a satellite.

  @madmax44 

The primary router must be from the Deco family, to work together with E4 as Satellites. Considering what you have, I would recommend M4, M5, or M9Plus as your primary unit. 

With that setup, expect to see speeds up to 600Mbps from Main Deco and about half of that from Satellite E4s. It is because you will be hitting limitations of WiFi5, which is top supported protocol for all these Deco models.

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If you want to get better WiFi speeds to utilize your gigabit Internet link, you would need to put aside (decomission) your E4s and buy instead 2- or 3-unit set of Deco X50 or Deco X55. 

These are WiFi6 capable, Main Deco X50/X55 can deliver gigabit WiFi (Satellites will deliver somewhat less).