@mdzh Before I answer that, please tell if you configured Deco WiFi with same SSID as Archer WiFi, or they have different SSID?

@mdzh You should turn off WiFi in Archer C7 and only use WiFi from Deco. Archer C7 router manages your home network (IP address allocations, etc., etc.) while Deco in AP mode covers your place with...

@Philbert Note he specified "Model: Deco E4," which has 100Mbps Ethernet ports. As long as his Main Deco is E4, 90Mbps is all he can get for Internet connection made through Deco.

@Jka21 Download and Upload numbers that you see in Deco app are not speed test results. They show current WiFi network utilization. They are often low, and they are not real time. Unless you happen...

@Abdullabh Have you scrolled down to Frequently Asked Questions section of that article, and specifically Q4, Q5 and Q7?

@Abdullabh The following FAQ article by TP-Link may help: General questions about Ethernet Backhaul feature on your Deco