Xiaomi 4A Giga and Freeze Problem

Hi all newbie here,

I installed Openwrt two months ago and everything seems fine. Main reason that i would like to minimize bufferbloat. As you may know this device has 2 leds and both blue means everything is fine. But sometimes one turns orange and router freezes. Wifi broadcast also get lost. When this happens, i should disconnect and connect power and after reboot everything gets normal again.
One of my friend also has this device and he told he never reboot the device.
What can cause this and how to fix?