EC2可SSH但无法Ping/访问，Nginx端口绑定故障求助

背景 #

• 上传含无限循环的Node.js文件导致服务器崩溃，重启EC2实例后获得新IP；更新域名解析指向新IP后，浏览器访问IP可正常显示Nginx欢迎页
• 修改/etc/nginx/sites-available/domain.com配置文件，在server块添加新IP重定向规则后网站出现超时；移除该配置后，无法Ping通IP、无法查看Nginx欢迎页，网站依旧超时

Nginx启动错误信息 #

执行sudo nginx -c /etc/nginx/nginx.conf时输出以下错误：

nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Unknown error)
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Unknown error)
nginx: [emerg] bind() to [::]:443 failed (98: Unknown error)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Unknown error)
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Unknown error)
nginx: [emerg] bind() to [::]:443 failed (98: Unknown error)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Unknown error)
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Unknown error)
nginx: [emerg] bind() to [::]:443 failed (98: Unknown error)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Unknown error)
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Unknown error)
nginx: [emerg] bind() to [::]:443 failed (98: Unknown error)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Unknown error)
nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Unknown error)
nginx: [emerg] bind() to [::]:443 failed (98: Unknown error)
nginx: [emerg] still could not bind()

已完成的排查操作 #

• 执行grep -r listen /etc/nginx/*，发现默认配置与domain.com的sites-available配置均监听80、443端口
• 删除sites-available中的默认配置文件并重启Nginx，当前仅domain.com配置监听80、443端口，但问题未解决
• 重启UFW并确认已启用Nginx Full、HTTP、HTTPS规则，排除防火墙因素
• 仅能通过SSH正常连接服务器；浏览器访问服务器IP时会缓慢重定向到域名，随后超时

当前状态 #

99%确定故障与Nginx相关，已查阅大量资料仍无法解决，恳请协助排查。

内容的提问来源于stack exchange，提问作者Texas12