一、备份现有apt源配置

mv /etc/apt/sources.list /etc/apt/sources.list.old

二、替换为其他apt源
1、替换为默认官方源

这是一条命令，全部复制后，直接粘贴然后一起执行。

cat > /etc/apt/sources.list << EOF
deb https://deb.debian.org/debian/ bullseye main contrib non-free
deb-src https://deb.debian.org/debian/ bullseye main contrib non-free

deb https://deb.debian.org/debian/ bullseye-updates main contrib non-free
deb-src https://deb.debian.org/debian/ bullseye-updates main contrib non-free

deb https://deb.debian.org/debian/ bullseye-backports main contrib non-free
deb-src https://deb.debian.org/debian/ bullseye-backports main contrib non-free

deb https://deb.debian.org/debian-security/ bullseye-security main contrib non-free
deb-src https://deb.debian.org/debian-security/ bullseye-security main contrib non-free
EOF

2、替换为清华源

这是一条命令，全部复制后，直接粘贴然后一起执行。

cat > /etc/apt/sources.list << EOF
deb https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye main contrib non-free
deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye main contrib non-free

deb https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye-updates main contrib non-free
deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye-updates main contrib non-free

deb https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye-backports main contrib non-free
deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ bullseye-backports main contrib non-free

deb https://mirrors.tuna.tsinghua.edu.cn/debian-security/ bullseye-security main contrib non-free
deb-src https://mirrors.tuna.tsinghua.edu.cn/debian-security/ bullseye-security main contrib non-free
EOF

3、替换为中科大源

这是一条命令，全部复制后，直接粘贴然后一起执行。

cat > /etc/apt/sources.list << EOF
deb https://mirrors.ustc.edu.cn/debian/ bullseye main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian/ bullseye main contrib non-free

deb https://mirrors.ustc.edu.cn/debian/ bullseye-updates main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian/ bullseye-updates main contrib non-free

deb https://mirrors.ustc.edu.cn/debian/ bullseye-backports main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian/ bullseye-backports main contrib non-free

deb https://mirrors.ustc.edu.cn/debian-security/ bullseye-security main contrib non-free
deb-src https://mirrors.ustc.edu.cn/debian-security/ bullseye-security main contrib non-free
EOF

4、替换为腾讯云源

这是一条命令，全部复制后，直接粘贴然后一起执行。

cat > /etc/apt/sources.list << EOF
deb https://mirrors.cloud.tencent.com/debian/ bullseye main contrib non-free
deb-src https://mirrors.cloud.tencent.com/debian/ bullseye main contrib non-free

deb https://mirrors.cloud.tencent.com/debian/ bullseye-updates main contrib non-free
deb-src https://mirrors.cloud.tencent.com/debian/ bullseye-updates main contrib non-free

deb https://mirrors.cloud.tencent.com/debian/ bullseye-backports main contrib non-free
deb-src https://mirrors.cloud.tencent.com/debian/ bullseye-backports main contrib non-free

deb https://mirrors.cloud.tencent.com/debian-security/ bullseye-security main contrib non-free
deb-src https://mirrors.cloud.tencent.com/debian-security/ bullseye-security main contrib non-free
EOF

使用腾讯云服务器时，可以选择腾讯云内网源，走内网不消耗公网流量。
5、替换为阿里云源

这是一条命令，全部复制后，直接粘贴然后一起执行。

cat > /etc/apt/sources.list << EOF
deb https://mirrors.aliyun.com/debian/ bullseye main contrib non-free
deb-src https://mirrors.aliyun.com/debian/ bullseye main contrib non-free

deb https://mirrors.aliyun.com/debian/ bullseye-updates main contrib non-free
deb-src https://mirrors.aliyun.com/debian/ bullseye-updates main contrib non-free

deb https://mirrors.aliyun.com/debian/ bullseye-backports main contrib non-free
deb-src https://mirrors.aliyun.com/debian/ bullseye-backports main contrib non-free

deb https://mirrors.aliyun.com/debian-security/ bullseye-security main contrib non-free
deb-src https://mirrors.aliyun.com/debian-security/ bullseye-security main contrib non-free
EOF

使用阿里云服务器时，可以选择阿里云内网源，走内网不消耗公网流量。
6、替换为Linode源（不支持HTTPS）

这是一条命令，全部复制后，直接粘贴然后一起执行。

cat > /etc/apt/sources.list << EOF
deb http://mirrors.linode.com/debian/ bullseye main contrib non-free
deb-src http://mirrors.linode.com/debian/ bullseye main contrib non-free

deb http://mirrors.linode.com/debian/ bullseye-updates main contrib non-free
deb-src http://mirrors.linode.com/debian/ bullseye-updates main contrib non-free

deb http://mirrors.linode.com/debian/ bullseye-backports main contrib non-free
deb-src http://mirrors.linode.com/debian/ bullseye-backports main contrib non-free

deb http://mirrors.linode.com/debian-security/ bullseye-security main contrib non-free
deb-src http://mirrors.linode.com/debian-security/ bullseye-security main contrib non-free
EOF

解决https报错的问题

apt install apt-transport-https ca-certificates