编译安装时遇到问题

主机环境：Ubuntu16.04
遇到问题：执行git clone --recursive https://github.com/alibaba/euler.git时，报错fatal: unable to access 'https://chromium.googlesource.com/chromium/llvm-project/llvm/lib/Fuzzer/': Failed to connect to chromium.googlesource.com port 443: Connection timed out
请问这个问题需要怎么解决，要配置代理服务器吗

Start with the reported `git clone --recursive https://github.com/alibaba/euler.git` command and the timeout while connecting to `chromium.googlesource.com` on Ubuntu 16.04. Investigate whether the failure is caused by the recursive dependency fetch or network access, then confirm that cloning and compilation complete successfully without the reported error.

Written by the indexing model from the issue text.