Wifi ping: tp-link tl-wdr3600 vs zyxel nbg6617

i switched from my old tp-link tl-wdr3600 (which i used for years), to a zyxel nbg6617, mainly for better sqm performance.

i noticed the ping on wifi is not as good, as it was before on my old device.

my wifi 5ghz ping on the wdr3600 was like lan, mostly <1 ms and in worst case 1ms

on the zyxel my ping jumps between 1-10 ms, sometimes even higher and i also have sometimes "time outs", but rarely.

the router is on the exact same spot as the old one was before and even on closer range i dont get even close to this ping... is this a known issue?

i know, there is a thread about this, where the reason is the scaling_governor, but even if i set it to performance, i dont get close to what it was before.