To see if it is actually rebooting, or if it is just some other quirk, you can follow the directions here to get a copy of your logs.
It will download a ZIP file. Look inside there for a file named “current”.
Search for lines that look like this:
2018-03-27_12:57:51.22836 4 INFO: Boot flags: 00000001 power-on
2018-03-27_12:57:51.22837 4 INFO: Boot attempts: 1
2018-03-27_12:57:51.22838 4 INFO: Software resets: 0
2018-03-27_12:57:51.22838 4 INFO: Watchdog timeouts: 0
2018-03-27_12:57:51.22839 4 INFO: Times started since boot: 1
2018-03-27_12:57:51.22839 4 INFO: Abnormal terminations since boot: 0
2018-03-27_12:57:51.22840 4 INFO: Last termination exit code: 0
Two things to look for:
- Groups of those statements with very close timestamps (less than a minute or so apart).
- Something other than the ‘power-on’ boot flag, number of boot attempts, abnormal terminations, etc., as shown above.
If you see either/both of those two things, then you likely have an issue that support will need to address.