Isn't upgrade windows under Network Wide>General? And I think it is just used for automatically scheduled firmware upgrades (ones scheduled by Meraki). I spot checked a few of mine and it seemed accurate. Obviously you'll want to check your network timezones as well since that could have an impact. And also factor in lag time for the devices to download the firmware and actually apply it. So many devices reboot after the scheduled time depending on how many there is. Here is the description of the upgrade window from the dashboard.
"Meraki releases new firmware approximately once a quarter. When new firmware is released, your network will be scheduled for an upgrade, and you will be notified 2 weeks in advance via email. Once scheduled, you have the option to reschedule.
While installing a firmware update, Cisco Meraki devices continue to operate normally until they reboot as the final step in the upgrade process. The reboot takes 1-2 minutes, so it is best to pick an upgrade time with minimal expected network usage."
Adam R MS | CISSP, CISM, VCP, MCITP, CCNP, ITILv3, CMNO
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