I have noticed strange behaviour of System health - temperature and voltage suddenly change very strong - to -2 C (see files)
What does it mean? Motherboard problems?
what kind of device do you have? which RouterOS version do you use?
We have RB450G with standard box and power supply unit.
RouterOS is ver.5.2
P.S.
These are reports from PRTG Network monitor (see below). Voltage sensor I turned on 1 hour before.
And I notice - then voltage/temperature go down, packets stop to go via the router.
For this sort of issue it is best to try and take a supout.rif both when the issue is occurring and when it is not, then send to support@mikrotik.com so they can analyse and attempt to replicate the issue.
Also ensure you’re running the newest version of the routerboard firmware.
Check this using
/system routerboard print
Upgrade (if needed) using
/system routerboard upgrade
It will tell you to restart when done.
Hope this helps 
Hello
My current-firmware is “2.29”
Is it last?
It should show you what your current is and what the version you can upgrade to is.. Edit: Corrected, each model has it’s own version numbers.
each model has a different “current” version