New policy in VirtualBox 6.1.28

[gregsmirnov]

VirtualBox doesn't allow a flexible IP range for host-only network interface starting from version 6.1.28. The default range 192.168.56.0/21 can be changed in /etc/vbox/networks.conf

https://virtualbox.com/manual/ch06.html#network_hostonly

[natemccurdy]

The default range in vagrant-auto_network can be changed by updating your Vagrantfile with the following:

AutoNetwork.default_pool = '192.168.56.0/21'

Put that before any Vagrant config lines.

You'll have to vagrant destroy -f all of your VM's and also rm ~/.vagrant.d/auto_network/pool.yaml before a vagrant up will work with the new range.