https://sansui-r.com从 DNS 到浏览器，按连接层定位通用网络故障，并用可回退的步骤验证恢复。zh-CNhttps://sansui-r.com/diagnosis/five-layer-route/https://sansui-r.com/diagnosis/five-layer-route/用五个可观察阶段替代“能不能上网”的模糊判断，快速确定下一步检查位置。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/diagnosis/baseline-record/https://sansui-r.com/diagnosis/baseline-record/用一份最小记录保存时间、错误、范围与环境，避免修改后失去可比较的基线。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/diagnosis/isolate-boundary/https://sansui-r.com/diagnosis/isolate-boundary/通过设备、网络和浏览器三组单变量对照判断故障更接近哪一侧。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/dns/lookup-failure/https://sansui-r.com/dns/lookup-failure/根据 DNS 的超时、NXDOMAIN、空回答和地址不符选择不同排查步骤。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/dns/cache-contamination/https://sansui-r.com/dns/cache-contamination/逐层确认缓存位置并保留回退，避免同时重置全部网络设置。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/dns/doh-comparison/https://sansui-r.com/dns/doh-comparison/在不长期改动系统设置的前提下，对照浏览器 DoH 与系统 DNS 结果。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/dns/ipv6-preference/https://sansui-r.com/dns/ipv6-preference/比较 A/AAAA、默认路由与连接结果，避免把双栈失败误判为 DNS 全面故障。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/dns/hosts-shadowing/https://sansui-r.com/dns/hosts-shadowing/在不泄露系统信息的前提下检查 hosts 是否覆盖正常 DNS 结果。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/transport/tcp-handshake/https://sansui-r.com/transport/tcp-handshake/区分没有及时响应的超时与目标明确拒绝连接，选择不同验证方式。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/transport/packet-loss/https://sansui-r.com/transport/packet-loss/用时间窗口、方向与对照链路记录间歇传输问题，不发布无依据排行。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/transport/mtu-black-hole/https://sansui-r.com/transport/mtu-black-hole/识别特定大小流量失败、握手后停滞与路径 MTU 发现异常。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/transport/gateway/https://sansui-r.com/transport/gateway/检查地址、默认路由和网关可达性，区分本地接入与更远路径。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/transport/tcp-udp-distinction/https://sansui-r.com/transport/tcp-udp-distinction/区分网页 TCP/QUIC 成功与语音、游戏等 UDP 流量受限的情况。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/web/tls-certificate/https://sansui-r.com/web/tls-certificate/不绕过警告，按域名、有效期、系统时间和中间证书定位 TLS 失败。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/web/http-status/https://sansui-r.com/web/http-status/根据响应类别区分跳转、客户端请求、权限限制与服务端错误。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/web/system-time/https://sansui-r.com/web/system-time/核对日期、时区与自动同步状态，安全恢复后再验证证书和会话。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/web/captive-portal/https://sansui-r.com/web/captive-portal/在公共网络中识别强制门户，避免把重定向或证书警告误判为站点故障。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/browser/profile-isolation/https://sansui-r.com/browser/profile-isolation/用临时配置文件区分扩展、缓存、Cookie 与系统网络问题。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/browser/proxy-conflict/https://sansui-r.com/browser/proxy-conflict/核对代理来源、自动配置脚本与扩展，恢复单一路径后验证。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/browser/service-worker-cache/https://sansui-r.com/browser/service-worker-cache/在不清空全部浏览器资料的情况下处理站点级离线缓存与旧资源。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/browser/extension-interference/https://sansui-r.com/browser/extension-interference/从内容拦截、代理、隐私与开发扩展中定位修改请求的组件。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/local-network/wifi-interference/https://sansui-r.com/local-network/wifi-interference/比较位置、频段、有线与其他设备，区分无线接入和上游故障。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/local-network/router-recovery/https://sansui-r.com/local-network/router-recovery/先保存配置和工作，再重启并逐项确认 WAN、地址、DNS 与无线状态。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/local-network/mobile-hotspot/https://sansui-r.com/local-network/mobile-hotspot/用小流量、短时间热点对照隔离接入路径，同时避免把恢复过度归因。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/local-network/firewall/https://sansui-r.com/local-network/firewall/识别应用、端口和方向限制，用可回退的最小规则验证。Fri, 14 Aug 2026 00:00:00 GMThttps://sansui-r.com/local-network/ethernet-fallback/https://sansui-r.com/local-network/ethernet-fallback/在同一局域网内用有线连接区分 Wi-Fi 接入问题与共同上游问题。Fri, 14 Aug 2026 00:00:00 GMT