You cannot reschedule maintenance.
However the Hub may be trying to update it's firmware and constantly failing?
Try a 60 second factory pinhole reset as below;
Remove any ethernet cables from the Hub and hold the pinhole reset switch for 60 seconds. Do NOT reboot the Hub, just let it do it's thing for 10 minutes. Note you will need the passwords from the bottom of the Hub afterwards, so make sure they are legible.
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