PortServer TS 4 H MEI rebooting during periods of higher heat

We have a location where the Portserver restarts itself continually during periods of higher temperature. This device has been replace 3 times and the last time a H MEI unit was used with the same results. Power supplies and power sources were changed and none of the other device are having issues (modems and router). We have many other locations with the same design/configuration and temperature with none of these issues. Configuration of the Portservers at these sites are similar to the one we are having issues with but with slight differences in the TCP/IP settings. Can the reboot of a Portserver be caused by errors on the serial or ethernet side of the connections? Is there any way to log why the device is rebooting? Thanks

This is something I would suggest you send an email to technical.support@digi.com about.