建议先做好备份

cp /etc/opkg/distfeeds.conf /etc/opkg/distfeeds.conf_back

找到系统-软件包-配置opkg
vi /etc/opkg/distfeeds.conf条目框内替换以下地址

src/gz openwrt_core http://mirrors.ustc.edu.cn/lede/releases/18.06.4/targets/x86/64/packages
src/gz openwrt_base http://mirrors.ustc.edu.cn/lede/releases/18.06.4/packages/x86_64/base
src/gz openwrt_luci http://mirrors.ustc.edu.cn/lede/releases/18.06.4/packages/x86_64/luci
src/gz openwrt_packages http://mirrors.ustc.edu.cn/lede/releases/18.06.4/packages/x86_64/packages
src/gz openwrt_routing http://mirrors.ustc.edu.cn/lede/releases/18.06.4/packages/x86_64/routing
src/gz openwrt_telephony http://mirrors.ustc.edu.cn/lede/releases/18.06.4/packages/x86_64/telephony

保存后进LEDE后台执行：

echo "nameserver 223.5.5.5">/tmp/resolv.conf
rm -f /var/lock/opkg.lock
opkg update