Hello,
it seems there are still issues at least with some mirrors trying to download VyOS images. It was impossibile to contact (at least for me) these mirrors:
http://0.us.mirrors.vyos.net/vyos/iso/release/1.0.3/vyos-1.0.3-amd64.iso
http://0.de.mirrors.vyos.net:82/iso/release/1.0.3/
Thank you
Adriano