I sort of stumbled on to this, as I restarted the Windows SNMP service after making a settings change (location) … but no reboot of the computer. However, LibreNMS detected this as a reboot (it wasn’t!). Tried it again on a second PC to make sure … yep, consistent.
Yes that will happen since you are making to changes to the snmp service and Windows will restart the service automatically which will reset the up time.
Ahh - OK, so it looks at the service uptime, not the machine uptime … right? No biggie, it was just funny to see my machine as “rebooted”, even though it wasn’t. LOL.