I've never seen it either.
Nothing specific in the log. 192.168.0.100 is a local computer that logs into the DNR-202L to view.
I can get some info on through a google search. I'm not sure if that relates to the DNR-202L.
This menu allows to configure system to reboot, when an specific IP address does not respond, or when it detects, that the software has locked up. The detection is done in two ways: Software watchdog timer (mostly caused by hardware malfunction) device can recover itself with reboot.Oct 13, 2017
Manual:System/Watchdog - MikroTik Wiki
https://wiki.mikrotik.com/wiki/Manual:System/Watchdog
2017/11/15 06:20:24 admin login Ok from 192.168.0.100
2017/11/15 02:37:00 usb1 mounted successfully.
2017/11/15 02:36:51 network set to DHCP
2017/11/15 02:36:45 system power on.
2017/11/15 02:36:18 system watch-dog reboot.(code 16)
2017/11/14 13:52:16 admin login Ok from 192.168.0.100
2017/11/14 09:35:08 admin login Ok from 192.168.0.100
2017/11/14 09:34:50 network set to DHCP
2017/11/14 09:34:41 network port connected.
2017/11/14 09:34:40 network port disconnected.
2017/11/14 09:33:49 usb1 mounted successfully.
2017/11/14 09:34:00 system set to new time 2017/11/14 09:33:49.
2017/11/14 09:33:45 network set to DHCP
2017/11/14 09:33:39 system power on.
2017/11/14 09:33:06 system abnormal power off.
2017/11/14 09:25:08 admin login Ok from 192.168.0.100