I am experiencing a speed limitation issue with my network setup. My internet plan provides 300 Mbps, but when I connect my Archer C6 router to the Deco M5 (from ACT Fiber) via Ethernet, the speed is capped at 10 Mbps.

I have attempted modifying system parameters but haven't had any success. Even when using a direct LAN connection from the router, the speed remains restricted to 10 Mbps.

However, when I connect the same WAN cable directly to my laptop, I get the full 300 Mbps speed.

Could you please assist me in resolving this issue?