When I first installed OpenWrt on my 2 R7800 they weren't stable. They crashed/rebooted within a week or so.
I found several posts discussing similar behavior and found a solution by adding the lines below in the local startup script.
> # Ondemand Governor Tweaks > echo ondemand > /sys/devices/system/cpu/cpufreq/policy0/scaling_governor > echo ondemand > /sys/devices/system/cpu/cpufreq/policy1/scaling_governor > echo 800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq > echo 800000 > /sys/devices/system/cpu/cpu1/cpufreq/scaling_min_freq > echo 35 > /sys/devices/system/cpu/cpufreq/ondemand/up_threshold > echo 10 > /sys/devices/system/cpu/cpufreq/ondemand/sampling_down_factor > echo 1000000 > /sys/devices/system/cpu/cpufreq/ondemand/sampling_rate
21.02 is around the corner (I secretly installed it). Are these lines still necessary in 21.02?