Sophos UTM 9 as a VM (free license version) *not* autostarting in ESXi 6.5

[EDITED]

Hello Sophos Community,

I have been using Sophos UTM 9 (free license) as a VM on ESXi 6.5 for a couple of months now, but one problem remains:

while autostart is enabled on ESXi and all VMs start automatically after a brownout or power outage, the Sophos VM is the only one that remains switched off, no matter whether it is started first or last in the sequence, and with various delays between each machine boot (30, 60, 90 seconds). So it doesn't seem to be caused by a vmnic that wouldn't be up and running yet.

As for allocated resources, the Sophos VM runs on two vCPUs and 8Gb RAM. And it has VMWare Tools already installed.

Could it be that the Sophos VM just don't interpret correctly the autostart signal sent by ESXi, while understanding it when sent manually through the ESXi web interface? And why would it be so?

Any idea for a solution, anyone?

Thank you!

bhleblanc