KVM - Virtual net Interfaces disabled after rebooting virtual machine

Hello.

I have a Cloudmin KVM installed and i am experiencing a recurrent with system's virtual network interfaces. When i do add virtual interface to a system using the Cloudmin UI, it seems to work fine, but after rebooting the virtual system it doesn't come back. Cloudmin states that it's not active.

I tried to configure the network manually using virtual system webmin to enforce that the virtual interfaces should be turned on during startup, but after a reboot it doesn't seem to have any effect. So all the times i need to go to cloudmin panel and re-add the virtual interface.

Does anyone know what might be wrong?

Thank you

Luciano