I've pushed a new box with version 8.6.1 who should fix the bug ( I tested it in a Virtualbox 5.0.* env and the network works properly)
It works here too - thanks for the quick fix. I'm still on VirtualBox 5.0.26 and Vagrant 1.8.4 because of Vagrant bug #7610 (support for VirtualBox 5.1 was first added in Vagrant 1.8.5).
Best regards, Laurențiu https://github.com/mitchellh/vagrant/issues/7610
