这是一个怎样的故障场景？

What does this pattern look like?

这是一个匿名化的排查场景：搬进新住处后，路由器看起来正常，手机也能上网；但电脑接网线或近距离测速始终上不去。问题可能出在网线、墙口、路由器 LAN 口或设备网卡，其中任何一个环节只支持或协商为 100 Mbps，整条测试路径就会被它限制。

This is an anonymised diagnostic pattern. The router looks healthy and devices connect, yet a wired computer or nearby WiFi test never improves. One cable, wall port, LAN port or network adapter negotiating at 100 Mbps can constrain the whole path.

四步排查顺序

A four-step check

1. 01在电脑的网络状态中查看链路速率。若显示 100 Mbps，先不要把问题归因给套餐。
2. 02用一根已知可用的 Cat5e 或更高规格短网线，直接连接电脑和路由器 LAN 口做对照。
3. 03换一个 LAN 口；再检查电脑是否接在扩展坞、旧交换机或墙面跳线后面。
4. 04只有链路已显示 1 Gbps 或更高、且仍明显异常时，才记录测试条件并向运营商或技术人员继续排查。

1. 01Check the link speed in the computer's network status. A 100 Mbps link is already a useful clue.
2. 02Use a known-good Cat5e-or-better short cable directly between the computer and a router LAN port.
3. 03Try another LAN port and remove docks, old switches or wall jumpers from the test path.
4. 04Only after the link shows 1 Gbps or higher should you collect test conditions and investigate the service layer.

避免两个常见误区

Two common mistakes

第一，不要在未确认链路前反复恢复路由器出厂设置，这会让原有配置丢失却未必改变物理瓶颈。第二，WiFi 测速本来会受设备、距离和干扰影响；要判断千兆服务是否经过有线链路，优先做单设备、近端、无扩展设备的对照测试。

Avoid factory-resetting a router before checking the link: it can erase working configuration without changing a physical bottleneck. Also, WiFi tests vary with device, distance and interference; use a single-device, short-path wired comparison when assessing the service.