服务器 make install_ssl 的时候提示超时：

[Fri Oct 20 10:26:11 UTC 2017] GET
[Fri Oct 20 10:26:11 UTC 2017] url='https://acme-v01.api.letsencrypt.org/directory'
[Fri Oct 20 10:26:11 UTC 2017] timeout
[Fri Oct 20 10:26:11 UTC 2017] _CURL='curl -L --silent --dump-header /var/www/ssl/http.header '
[Fri Oct 20 10:27:32 UTC 2017] Please refer to https://curl.haxx.se/libcurl/c/libcurl-errors.html for error code: 35
[Fri Oct 20 10:27:32 UTC 2017] ret='35'
[Fri Oct 20 10:27:32 UTC 2017] Can not connect to https://acme-v01.api.letsencrypt.org/directory to get nonce.
[Fri Oct 20 10:27:32 UTC 2017] Register account Error: 
[Fri Oct 20 10:27:32 UTC 2017] _on_issue_err
[Fri Oct 20 10:27:32 UTC 2017] Please add '--debug' or '--log' to check more details.
[Fri Oct 20 10:27:32 UTC 2017] See: https://github.com/Neilpang/acme.sh/wiki/How-to-debug-acme.sh
[Fri Oct 20 10:27:32 UTC 2017] Diagnosis versions: 
openssl:openssl
OpenSSL 1.0.1f 6 Jan 2014
apache:
apache doesn't exists.
nginx:
nginx version: nginx/1.10.2
built by gcc 4.8.4 (Ubuntu 4.8.4-2ubuntu1~14.04.3) 
built with OpenSSL 1.0.1f 6 Jan 2014

经过不断测试查询原因，找到问题所在。是因为部分主机的默认 MTU 值和 docker 的默认 mtu 值不一致导致部分请求超时。

但是我不能更改，改了，一改就挂，不知道怎么解决？我的系统是 ubuntu14.