It seems that from a certain point in time the official VyOS current vagrant box images (https://app.vagrantup.com/vyos/boxes/current) are broken in some may (I’m using libvirt ones).
vagrant up is stuck at:
vy1: Warning: Authentication failure. Retrying...
I tried to force the Vagrantfile for having:
vy1.ssh.username="vyos" vy1.ssh.password="vyos"
but nothing changes.
Most probably this is due to missing vagrant default public key? (or the box configuration?)