rt-ac5300 packet loss

Hi, First post here, I hope I am not breaking any rule. I have a RT-AC5300 running Asus-Merlin 384.7_2. It is mostly working great, and better than my old WRT-AC1900acv2 with dd-wrt used to. Still, from time to time I hit this weird problem. Some of my machines looses 30-50% of the ping...