Very High Ping for ROCK PI 4

Hey,

I have a Raspberry Pi and a Rock Pi connected to the router through WiFi at the same time, and when I SSH to Rock Pi, I found that the input has some delay.

When I checked Ping, I found that its value was very high and the Raspberry Pi was very small.

What can I do to improve it?

My Rock Pi is working with Debian desktop (rockpi4_debian_stretch_lxde_armhf_20181105_2120).

sudo iwconfig wlan0 power off

When I turned off the Power Management, the situation improved, but it was still worse than the Raspberry Pi.