Looks like you are either using an outdated version of GVM itself or an outdated version of the greenbone-nvt-sync script which is still trying to download the feed via HTTP from a system which isn’t available anymore:
Looks like you are either using an outdated version of GVM itself or an outdated version of the greenbone-nvt-sync script which is still trying to download the feed via HTTP from a system which isn’t available anymore: