Failed to access 'default_netvm' property

[Johnboy]

No, same error.
I cloned sys-net, deleted sys-net and ran qubesctl state.apply qvm.sys-net as mentioned here:

How to create new sys-net?

Well, you’ll also need to set “Net qube” to none,Mode to “HVM”, disable memory balancing, set “autostart”, adjust memory, and enable clock-sync. Then you’ll need to attach your NICs, and possibly configure strict reset. Alternatively, run : qubesctl state.apply qvm.sys-net I suggest you clone the exiting sys-net before deleting it. I never presume to speak for the Qubes team. When I comment in the Forum or in the mailing lists I speak for myself.