I have the following setup

X60 (Main deco)

X20 (3 nodes) connected to primary deco.

1gbps cables

Internet plan (500mbps)

ISP modem (Archer C5 - 1.2Gbps Wi-Fi speed, 300Mbps 2.4GHz, 867Mbps 5GHz)

The setup to my PC is as follows (lets call this my Ideal Setup)

ISP Fiber cable -> Main Deco (X60. Setup as PPPoE) -> Archer C5 Modem (Router mode) -> MyPC

I am using the archer c5 like a network switch, to be able to get more ethernet ports connected to my Main Deco

Scenario 1: Connect MyPC to Main Deco directly

- Getting correct speed (500mbps as per plan)

Scenario 2: Connected as per Ideal Setup

- Getting 100mbps in most cases (Due to auto-negotiation issue. I am 100% sure this is the issue)

- And getting correct speed in some cases (upon restart. But goes back to 100mbps automatically after a while?)

- There is no cable issue between Main Deco to Archer C5 modem

I need a way to override this auto negotiation setting between Main Deco and Archer C5 modem.

- I have tried searching this in Deco's app and web interface, but I don't see any visibility of the auto negotiation values, nor an option on how to change this.

- I am looking for an interface like this article  - What if my Router Speed is capped at 100 Mbps? - Home Network Community

Attaching my current interface