Updated: - If you have QoS issues like other people, you can switch to "Access Point Mode" so QoS will be completely disabled. Your network speed will be back to normal, the weak point is that you...

@Hovercraft Thank you so much! It worked! I was very disappointed in my Deco M4 until I followed your comment. TP-Link Team should find a way to fix this problem as soon as possible. Although this...