Cisco VPN :: ASA 5500 - Way To Soft Reboot Automatically

Before nearly four years we have purchased 4 Cisco ASA 5500 Device for our organization.Out of these four device currently two are active in field and other two we kept as a spare.Now, in one active device we are facing very rare and strange issue.

The device automatically soft reboot once in nearly 60 days and we do not have any pre or post symptoms of this incident only server logs providing us this information.The device itself located in very controlled environment in a data center where physical tampering or temperature waviness is not possible.

We also asked one Cisco Expert from data center but still issue is not solved.Before two month, using remote syslog service we also started log redirection to a server so that when such incident occurs we have something to analyze but it is worthless log has nothing to tell us.

My questions are

1. "It is a hardware fault or software issue?"

2. "Is it possible with Cisco 5500 that automatically it reboots due to some internal hardware/software issue, if yes how we can trap or monitor it?

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