Thank you for your tips. You're right, the wifi performance immediately gets back to normal once the wifi is off. But it is not an ultimately solution yet because I need to use my AirPods and Apple...

@Klaudiusz I've spent days with TP Link technicals for remote troubleshooting. However, they couldn't find where the issue from while all the settings and status have no issue! What they said were...

I bought 4pcs of P7 for my home at end of Aug this year and they were working fine for 1-2 months. However, we noticed 2 issues as below. 1) Sine recent weeks the internet connection is very poor...