RESOLVED: Router reboot without proper shutdown

Hi!

So, our router (CHR 6.34.3) is occasionally crashing / rebooting. The crash times match with our backup solution:
$name = router.hostname
$output = /backup/path
ssh admin@$name export file=$name
sftp admin@$name:$name.rsc $output/

We first configured the backup to run at 00:00 and we experienced 3 crashes in 1 month, at 00:00.
We have now moved the backup to 01:00 and have experienced 1 crash in 3 weeks, at 01:00.

I have now disabled the backup and will monitor if the issue is resolved..

What would be the proper way of identifying / debugging / resolving the problem?
The logs don’t say much - only “router rebooted without proper shutdown”. What triggered the shutdown?

Thanks in advance!

Support suggested an upgrade. I have upgraded to v6.35.1. The router did not crash since the upgrade - 3 weeks in.