你好。我尝试在 Ubuntu 服务器（确切地说是 Ubuntu 20）上安装 Discourse，但每次都会收到“警告：计算机的 443 端口似乎无法通过主机名访问”的错误。我尝试了多种解决方案，也查阅了很多资料，但仍未找到解决办法。这是我第一次设置 Discourse 服务器，所以不太确定自己哪里做错了或问题出在哪里。完整错误信息如下：
root@vps-zap581523-2:/opt/discourse# ./discourse-setup
Ports 80 and 443 are free for use
'samples/standalone.yml' -> 'containers/app.yml'
Found 4GB of memory and 20 physical CPU cores
setting db_shared_buffers = 1024MB
setting UNICORN_WORKERS = 8
containers/app.yml memory parameters updated.
Hostname for your Discourse? [discourse.example.com]: forum.mayflowerleti.org
Checking your domain name . . .
./discourse-setup: line 36: curl: command not found
WARNING: Port 443 of computer does not appear to be accessible using hostname: forum.mayflowerleti.org.
./discourse-setup: line 36: curl: command not found
WARNING: Connection to http://forum.mayflowerleti.org (port 80) also fails.
This suggests that forum.mayflowerleti.org resolves to some IP address that does not reach this
machine where you are installing discourse.
The first thing to do is confirm that forum.mayflowerleti.org resolves to the IP address of this server.
You usually do this at the same place you purchased the domain.
If you are sure that the IP address resolves correctly, it could be a firewall issue.
A web search for "open ports YOUR CLOUD SERVICE" might help.
This tool is designed only for the most standard installations. If you cannot resolve
the issue above, you will need to edit containers/app.yml yourself and then type
./launcher rebuild app
root@vps-zap581523-2:/opt/discourse#
目前我不知该如何继续。VPS 所有者已将 DNS 指向我们运行 Discourse 的 VPS IP 地址，但问题仍未解决。他还告诉我没有防火墙阻止连接，因此我不太清楚为什么无法正常工作。如果能得到一些帮助，那就太好了。抱歉又创建了这样一个主题，但目前我确实没有其他选择。感谢您的时间和帮助。
