This is a scheduled reboot of our core equipment to improve uptime during business hours. The hardware vendor has issued a software bug for the issue and firmware will be released in the coming weeks. We have asked for early access if it becomes available.
The restarts are due to the data plane tries to program QoS policy when interfaces are dynamically created/deleted. These can happen when the data plane is busy and loaded although we are not seeing this behaviour.
We will schedule a planned upgrade of the firmware when it is released.