I have an RB532A with a 564 Daughter board, I upgraded the Firmware to 2.16 and router OS to 3.16. It has two SR5 and one XR3-3.7. I have checked and double checked all of the configurations and have not found any problems. We have various other 532A with identical configurations and are working without a problem. This only occurs under load and it can happen various times within an hour under peak, with minimal load it can last for days without a reboot. We have 532A that have been working non stop without a reboot for months. I have read and checked all of the RouterBoard and Mikrotik Forums and tried all of the fixes that might help without any success.
Please Help Us!!
Replace the power supply with a quality 48vdc adapter. Make sure the appropriate jumpers are set before doing this.
Already replaced the Power Supply. That was the first thing I did.
The message after the reboot is the Following:
router was rebooted without proper shutdown by watchdog timer
I turned off the watchdog timer to see what was the effect, and the effect was that it lost connectivity until I physically went to the site and reset it manually. I have an autosupout file that was generated by the watchdog.
Try coming back to 2.9.51 
)
i have exactly the same problem with almost the same config.
MikroTik RB532A with daughterboard.
ive upgraded the firmware, all software packages, performed a complete reset, replace the PoE with normal power supply, disabled devices not in use etc etc etc.
No solution as yet, still struggling with issue… Anyone with similar issues?
what does your log show?
Jan/01/2002 03:00:03 router was rebooted without proper shutdown by watchdog timer.
I had an open session just before it happened- There was 8Mbps traffic between two Ethernet interfaces.
I’ll double check the temperature, power adapter etc.
I have an RB532 with RB564 that feeds our in building business customers. It has been running for about 2 years in this function. All ports have been in use. It has seen about 20Mbps of throughput. Power is 12vdc 4 amp adapter plugged into the power jack.
Current uptime is 91 days. I had uptime of about 360 days on ROS 2.9.50 before upgrading to 2.9.51.
No problems at all with this setup. I am not about to upgrade beyond 2.9.xx as this is the definition of stable.
Tom