proxmox repository

deb http://kartolo.sby.datautama.net.id/debian stretch main contrib non-free
deb http://kartolo.sby.datautama.net.id/debian stretch-updates main contrib non-free
deb http://kartolo.sby.datautama.net.id/debian-security/ stretch/updates main contrib non-free
deb http://download.proxmox.com/debian/pve stretch pve-no-subscription

disable /etc/apt/sources.list.d/pve-enterprise.list

disable apt update ipv6

nano /etc/apt/apt.conf.d/99force-ipv4
Acquire::ForceIPv4 "true";

apt update; apt dist-upgrade