The end users are reporting that randomly they will get redirected to gstatic.com/generate_204. Looking the browser history under gstatic.com/generate_204 it references "Fortinet DNS Service" which made me wonder if it was one of the Security Profiles causing the issue. I removed all profiles...
简单解释, 当你的操作系统连接特定 HTTP 服务, 比如 http://www.gstatic.com/generate_204, 如果能够返回 204 状态码, 那就基本说明你连接上网络了. 如果被 301, 说明你已经有 IP, 但是你的网络可能是一个付费网络, 会跳转到一个页面让你付钱/登陆. 如果无法解析域名/创建 TCP 连接, 说明你的三层/四层网...