I would propose to generate a QKVIEW Support File and Upload this to iHealth.
You could look through the Diagnostic Screen to check if some issues look related to your Problem.
Also the Log Search in iHealth is a good way to filter the logs to Error Messages and above.
If you don't find any hints related to your problem open up a Support Case.
You can Link the QKVIEW to the Support Case so the Support Engineer has a good view on your System.
Besides the Reboot Issue you should think about updating the System(s) to 12.1.2 HF2.
This is the most actual release your Hardware Plattform supports (3600 is already EoSD)