My solution for my problems. I sold all of my TP-link equipment. Bought Fritzbox Wifi 6 extenders. Works like a charm. Never TP-link again.

I'm losing my F'in MIND here. I have 5 Deco's (mix of m5 and 1 m9 main deco). There is always 1 deco that chooses to work wireless instead of wired. Solution? Pull of power cable and reconnect. But...