vagrant xenial box is not provided with vagrant/vagrant username and password
It is Vagrant convention that the default user is named "vagrant", and a whole host of scripts assume this to be the default.
The xenial box is substantially less useful to Vagrant users with the "ubuntu" user as the default, and there is limited benefit to having the "ubuntu" user.
 Search for "user to SSH" in https:/
|Changed in vagrant:|
|status:||New → Invalid|