Did you ever manage to use Whonix without a proxy? Could be the case of simple user error.
- Whonix doesn’t create a new network adapter. It has no access to the host operating system.
- VirtualBox might create a new network adapter on the host operating system, but it’s virtual network settings are configured to use NAT so this does not happen.
- (KVM (different virtualizer) does create a network adapter unfortunately. ([Help Welcome] KVM Development - staying the course - #546 by Patrick))
Try Tor Browser inside VirtualBox. In theory, this also shouldn’t work if VirtualBox was to create its own network adapter.