修改源/etc/apt/sources.list加速

deb http://mirrors.aliyun.com/raspbian/raspbian/ buster main non-free contrib rpi firmware
deb-src http://mirrors.aliyun.com/raspbian/raspbian/ buster main non-free contrib rpi firmware

还有 /etc/apt/sources.list.d/raspi.list

deb https://mirrors.ustc.edu.cn/archive.raspberrypi.org/debian buster main