全志F1C100s Linux 系统编译出错：不能连接 github

环境

Ubuntu 20.04 LTS 64 位虚拟机

开发板：Lichee Pi Nano 

源代码：GitHub - florpor/licheepi-nano

问题描述

该源码库使用了 git 子模块的概念，一个库中包含了 u-boot、Linux等代码库。不需要分别编译，一个 make 全搞定

编译时提示错误：

>>> linux-headers b18adeb1e60bba3d6aa77e302673b38c41fd5c77 Downloading
Reinitialized existing Git repository in /home/user/sambashare/florpor/licheepi-nano/buildroot/dl/linux/git/.git/
Fetching all references
fatal: unable to connect to github.com:
github.com[0: 20.205.243.166]: errno=Connection timed out

Detected a corrupted git cache.
Removing it and starting afresh.
Initialized empty Git repository in /home/user/sambashare/florpor/licheepi-nano/buildroot/dl/linux/git/.git/
Fetching all references
fatal: unable to connect to github.com:
github.com[0: 20.205.243.166]: errno=Con