unrequested reboot of EX2300

Hi, we have three EX2300 switches (2x 48T , 1x 24P). Today all three switches performed an unrequested reboot, all of them within only some minutes. It was the second time that this happened.

All switches are running "18.3R1.9",

All show "Last reboot reason 0x20000wizzle reboot".

All show "% sysctl hw.re.reboot_reason

hw.re.reboot_reason: 131072".

Any ideas what is going wrong here?

Thank you for your help
Regards