VirtualBox 5.0 cannot access any network with Ubuntu Mate 15.04 host

Question

It's my first question I've asked here, but I've been a long time reader of Stack Overflow.

I use Vagrant with VirtualBox to handle the server configurations of the several projects I'm working on. I've used VirtualBox and Ubuntu Mate for the last few months without any problems. But I've changed my hard drive yesterday and I had to reinstall Ubuntu Mate 15.04.

I've installed the build-essential package, VirtualBox 5.0 from the x64 package found on VirtualBox's website and Vagrant from Vagrant's website. I've pulled my old VagrantFile from GIT and relaunched the machine. Vagrant pull the correct image, as expected, but once the VM is running in VirtualBox, Vagrant can't ssh into it.

I used VirtualBox's interface to get into the guest's shell, and found that I could not access any network. Even VirtualBox auto-update tool cannot connect to the internet. I get the message :

The network operation failed with the following error: Unknown reason

I've formated my computer several times using different versions/flavors of Ubuntu to no avail. I've also rolled back to previous versions of VirtualBox, but no luck either. I've manually installed a guest with VirtualBox and the network is not working either.

I've did several searches on Google and Stack Overflow for similar problems, but the closest matches were for Windows 10 issues. But neither the host or the guest is running Windows.

My computer/os configuration is the same as before yesterday, except for the drive change. I don't understand why it isn't working as before.

Here's my VagrantFile if it can help you :

# -*- mode: ruby -*-
# vi: set ft=ruby :

VAGRANTFILE_API_VERSION = "2"

Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|

  config.vm.box = "ubuntu/trusty32"

  config.vm.network "private_network", ip: "192.168.33.15"
  config.vm.network "public_network", ip: "10.1.1.207", bridge: "p4p1"

  config.ssh.forward_agent = true

  config.vm.synced_folder "src/", "/var/www/project",
    owner: "www-data", group: "www-data"

  config.vm.provider :virtualbox do |vb|
    vb.customize ["modifyvm", :id, "--memory", "512"]
  end

  config.vm.provision "shell", path: "bin/shellprovider.sh"
end

Any help or any hint would be greatly appreciated.

Regards,

Eric Lacasse