Problem description:
When I load the outgoing (upload) traffic (e.g., uploading large files, live streaming, or torrenting), the wired internet connection drops on my PC, but Wi-Fi remains stable. After physically reconnecting the Ethernet cable, the internet immediately returns. This happens only on wired connection — Wi-Fi never drops.

Steps to reproduce:

1. Start heavy upload (e.g., 80-100 Mbps upload speed).
2. After 10-30 seconds, wired connection fails (no internet on PC).
3. Wi-Fi on other devices works fine.
4. Reconnect Ethernet cable → internet restored instantly.
   What I tried:
   ✅ Swapped Ethernet cable
   ✅ Fixed duplex on PC: 1 Gbps Full Duplex (disabled Energy Efficient Ethernet and Green Ethernet).
   ✅ Disabled QoS in router settings.

   System details:

   Router: TP-Link Archer AX53 (V1), firmware 1.6.2 Build 20260119.
   Windows 11.
   ISP speed: 100 Mbps down / 100 Mbps up.
   Question:
   Why does the wired connection drop only during upload while Wi-Fi works fine? Is this a duplex mismatch, buffer overflow, or a firmware bug? How can I fix it without downgrading firmware?