Strange, I’ve been using NSS-builds for the last month and didn’t face any random reboots (2.4ghz is stable out of the box without any caldata or board-2.bin modifications). You mentioned you were using 24.10.4, I assume that’s the official version of openwrt? If so I’d suggest giving August Lorenzo’s build a try to see if that fixes reboot.
Alternatively you could try the exact build I’m running (my fork of august’s repo) to see if it fixes issue (Since I can confirm the router doesn’t reboot randomly on this build) Link. Just after flashing sysupgrade.bin, on first boot Login via gateway 172.17.0.1 (I Changed this in my build) then Luci --> System --> Custom Commands --> "Fix 5ghz Calibration Data (RAX120v2)" | the router will reboot by itself once the fix is applied. It’ll run this script to fix caldata and replace board2.bin (my fw ships board2.bin inside the sysupgrade firmware). Give it a try to see if this fixes random reboots.
Also I noticed your’re using manual pwm values to change fan speed. I’d suggest switching to closed loop to control fan speed since that’s the way stock oem firmware uses. (You can find the fan documentation here from this link. If you do flash the build from my repo, it should by default run the fan on auto configuration and speed would scale linearly with increasing temperature (it uses this fan script – but do note my fan script sometimes causes issues with openwrt 24.10 versions (for some reason g762 fan controller bugs out an reports fan1_input as 0, though it runs very stably on openwrt 25). Moreover you can see more custom commands in Luci --> System --> Custom Commands which you could use to manually choose fan speed if you so want.
You can have a look at all the custom modifications I made in my build here.
Hope this fixes your issue.