Edgecore ECS-4210 disappearing from network, but still switching

My ecs-4210 keeps disappearing in less than 24 hours from the network. No response to ping, and all arp tables gone.

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However it's still happily routing packets.

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Nothing in google to suggest if this is a known issue or not.

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Vlan 1, no network segregation, rebooting the unit brings back the GUI, SSH, telnet etc.

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Suggestions on methodology to fix?