I'm going to move this to the NPM space to get better visibility.
Solarwinds alerted "s3928 rebooted at xxxx ",When Itelnet that switch ,I can't find any reboot information from debug, and the switch display that system uptime is a long time ,So It's
strange .Solarwinds give a different result with that switch.
I have seen similar issues before particularly with Shoretel switches. Some sort of nightly maintenance that the Shoretel switches performed caused a cleanup that made SNMP think that the last boot time had changed. I have seen it from time to time with other devices but the Shoretel switches it happened every night.
This may have nothing to do with your problem but I have seen this behavior before due to a device. In my case it wasn't solarwinds misinterpreting data it was the data being collected was flawed.
could be a counter rollover for the uptime on the device
check the documentation on your device and see if it has anything documented on how it rolls over a counter and when if its there