使用 Proxmox repository 時，如果遇到類似以下的錯誤訊息，表示 CDN / DNS 可能有問題：
W: Failed to fetch http://download.proxmox.com/debian/pve/dists/bullseye/InRelease Cannot initiate the connection to download.proxmox.com:80 (2402:1f00:8000:800::467). - connect (101: Network is unreachable) Could not connect to download.proxmox.com:80 (51.79.159.216), connection timed out可以暫時將 download.proxmox.com 改為：
- jp.cdn.proxmox.com
- sg.cdn.proxmox.com
修改過後的 /etc/apt/source.list：
deb http://ftp.tw.debian.org/debian bullseye main contrib deb http://ftp.tw.debian.org/debian bullseye-updates main contrib # security updates deb http://security.debian.org bullseye-security main contrib deb http://jp.cdn.proxmox.com/debian/pve bullseye pve-no-subscription