One of my RB333 which I’m using as Nstreme2 bridge started to reboot several times per day. 
It worked perfectly for about 3 months but the last 2 months average uptime was only about 7 hours. I changed power adapters several times but it not helped. The power adapter is connected to UPS, and other devices works perfectly so I’m pretty sure that problem somewhere else.
In logs of RB333 I see “jan/01/1970 02:00:06 system,error,critical router was rebooted without proper shutdown (cause 1)”. Also there is autosupout.rif file overwrites everytime. Already tried to change RouterOS to v3.17 through many others.
/system resource print
uptime: 14m51s
version: “3.17”
free-memory: 51844kB
total-memory: 62232kB
cpu: “e300c2”
cpu-count: 1
cpu-frequency: 333MHz
cpu-load: 7
free-hdd-space: 40248kB
total-hdd-space: 61440kB
write-sect-since-reboot: 184
write-sect-total: 712
bad-blocks: 0
architecture-name: “powerpc”
board-name: “RB333”
I see that write-sect-total zeroed after unexpected reboot.
/system routerboard print
routerboard: yes
model: “333”
serial-number: “XXXXXXXXXX”
current-firmware: “2.16”
upgrade-firmware: “2.18”
Is there any way to fix stability without changing hardware?