@TP-Link Sorry for the late response. Yes, the PC was the only device connected with ethernet, and I also tried QoS with 1000 Down/Up. That was not the problem. I found out there was a setting called...

I didn't find my model in the drop down list, but it's the Deco W6000 v1.2 (2 pack), Firmware 1.0.2 Build 20210421 Rel. 65964. I have 800Mbps internet service and currently 15 connected devices, all...