I'm running VirtualBox on OpenSuse Leap 15.3 Gnome desktop installed from the OS repo. All of a sudden, all vboxnet (i.e. Host-Only) network interfaces are down on a host machine, even when a guest VM (a Debian Linux server in most cases) using one or more of them is running. I didn't change anything in my VirtualBox networking setup for years.
It is possible to manually bring up the interface with
ip link vboxnet1 set up
ip a add 1.2.3.4/24 dev vboxnet1
but it doesn't survive a reboot, of course.
I have been using NetworkManager all the time. I've tried to switch to Yast/Wicket setup with little success. I've also re-installed VirtualBox. Same thing.
Examining the Host Network Manager in VirtualBox didn't reveal anything. In fact, the VMs can communicate with one another. It's just a host-to-guest problem.
How does the "magic" of creating vboxnet interfaces is supposed to work? I'm out of ideas as to from which angle should this problem be approached.
