Case Studies案例研究 / Latest Case最新案例 The Router Port Lit Up and the Desktop Still Had No Internet: a Missing Network Driver After a Windows Reset (Occom 25M, Eastgardens)
路由器口的灯亮了，台式机却还是没网：重装系统后少了网卡驱动（Occom 25兆，Eastgardens）
On-site · Eastgardens上门 · EastgardensOccomOccom 澳世Opticomm fibre + PPPoEOpticomm光纤 + 拨号25 Mbps plan25兆套餐ASUS routerASUS路由器Missing network driver缺网卡驱动
The link light on the router came on the moment the cable went in, which is exactly why this one was confusing. A lit port means the cable and the two sockets are electrically fine — it says nothing about whether the computer can actually use the connection. Everything on the network side was healthy here. The fault was inside the desktop, and it had been created the day before.
网线一插上，路由器那个口的灯就亮了——这一单之所以让人困惑，原因正在这里。口亮只说明网线和两头的接口在电气上没问题，完全不代表电脑能用得上这条连接。这次网络侧每一段都是好的，故障在台式机里面，而且是前一天才产生的。
A lit port is not the same as a working connection
口的灯亮了，不等于这条连接能用
This is the single most useful thing to take from this job. When you plug a cable in and the router's port light comes on, three things have been proven: the cable is intact, the router's socket works, and the computer's socket is powered. That is all.
Everything above that — whether Windows can see the adapter, whether it has a driver, whether it can obtain an address — is invisible to that little light. So a lit port with no internet is not a contradiction. It is a fairly precise clue that the physical layer is fine and the problem lives further up, usually inside the computer.
这一单最值得带走的就是这句话。网线插上、路由器那个口的灯亮了，只证明了三件事：网线是通的、路由器的口是好的、电脑那个口是有电的。仅此而已。
再往上的所有事情——Windows 能不能看到这块网卡、它有没有驱动、能不能拿到地址——那盏小灯一概不知道。所以「口亮着但没网」根本不矛盾，它其实是一条相当精确的线索：物理层没问题，问题在更上面，而且通常在电脑里面。
Which link was actually failing真正出问题的是哪一环
Opticomm fibreOpticomm光纤
fine / 正常
→
Occom 25M / PPPoEOccom 25兆 / 拨号
fine / 正常
→
ASUS router & LAN portASUS路由器与网口
link light on / 口灯已亮
→
Desktop network adapter台式机网卡
no driver / 无驱动
Faulty here故障点
→
WindowsWindows系统
no connection / 无法联网
Four of these five links were doing their job, and the one that was not sits inside the computer where most network troubleshooting never looks. This is why we carry a test device: plugging our own laptop into the same cable and the same port took the entire network side off the table in under a minute, and left only one place for the fault to be.这五环里有四环都在正常工作，唯一有问题的那一环在电脑内部——而大多数网络排查根本不会看到那里。这也是我们随身带测试设备的原因：把自己的笔记本插到同一根网线、同一个口上，不到一分钟就把整个网络侧排除掉了，剩下能出问题的地方就只有一个。
How a system reset takes the network with it
重装系统为什么会把网一起带走
The customer had reset their Windows installation the day before. That is the whole story of this fault.
A fresh Windows install brings generic drivers for common hardware, but a desktop's onboard network adapter is one of the components most likely to come out of it without a working driver. And it is the worst one to lose, because the usual way to fix a missing driver is to download it — which you cannot do from a machine that has no network at all. The customer had also not been able to join the WiFi, which fits: the adapter, not the connection, was the thing that was broken.
If you are about to reset a desktop, download the network adapter driver from the manufacturer's site first and keep it on a USB stick. It turns this from a call-out into five minutes.
客户前一天刚把 Windows 重置了一遍。这个故障的全部来龙去脉就是这一句。
全新安装的 Windows 会带一批通用驱动，但台式机主板上的网卡，恰恰是最容易装完之后没有可用驱动的部件之一。而它又是最不该缺的那一个——因为解决缺驱动的常规办法是去下载，可你偏偏在一台完全没有网的机器上。客户当时连无线也连不上，这一点正好对得上：坏掉的是网卡这一侧，不是那条网络。
如果你正准备重置一台台式机，先去主板/网卡厂商官网把驱动下下来，存到 U 盘里。这能把一次上门变成五分钟的事。
How we isolated it on site现场怎么一步步定位
1
Checked the main router and its ports with our own test device先用自带的测试设备检查主路由器和端口
Router, cable and port all fine路由器、网线、端口都正常
2
Same cable, same port, customer's desktop — nothing同一根线、同一个口，换回台式机——没有反应
Fault is inside the PC故障在电脑本身
3
Looked at the network adapter in Windows进系统检查网卡状态
Driver not working网卡驱动异常
4
Customer mentioned the system had been reset the day before客户提到台式机前一天刚重置了系统
Explains the missing driver缺驱动的原因对上了
5
Downloaded and installed the network adapter driver下载并安装网卡驱动
Adapter now recognised网卡显示正常
6
Connection kept coming up then dropping接上主路由器后短暂连上又断开
IP allocation looked abnormal疑似IP分配异常
7
Reset the router and reconnected重置路由器后重新连接
Desktop stable and online台式机连接恢复正常
8
Replaced the wireless extender with a wired second router把无线扩展器换成有线副路由器
Wired to the PC, new SSID for the room有线直连电脑，房间多一个无线
The second problem, hiding behind the first
藏在第一个问题后面的第二个问题
Installing the driver got the adapter recognised, but the desktop still would not settle: it connected to the router and dropped again almost immediately, over and over.
Two faults in a row is more common than people expect, and it is easy to assume the first fix did not work. It had — the adapter was fine now. What we were looking at was the router handing out addresses abnormally, so we reset it and reconnected, and the desktop stayed up. The lesson is to check whether the symptom has actually changed after each step. "Still no internet" and "connects then drops" are different symptoms, and treating the second one as a failure of the first fix sends you backwards.
驱动装好之后网卡是认出来了，但台式机还是稳不下来：连上主路由器，几乎马上又断，反复如此。
一个故障后面跟着第二个，比大家以为的更常见，也很容易让人误判成「第一步没修好」。其实修好了——网卡这时候已经正常了。我们看到的是路由器分配地址不正常，于是把路由器重置后重新连接，台式机就稳住了。这里的经验是：每做完一步，都要看症状本身有没有变。「完全没网」和「连上又断」是两个不同的症状，把后者当成前一步没成功，只会让你往回走。
Fixing the coverage while we were there
顺手把房间覆盖也一起解决
The customer also had a WiFi extender in use. Extenders repeat the signal wirelessly, so whatever they receive is what they pass on — in a room the main router already struggles to reach, that means a weak signal repeated weakly.
There was a spare TP-Link router in the flat, so we configured it as a second router in the bedroom, fed by a cable rather than over the air. The desktop now plugs straight into it and tests fine, and the room gets its own wireless coverage as well. No new hardware was needed — just using what was already there in a better way.
客户家里还在用一台 WiFi 扩展器。扩展器是把信号无线中继一遍，它收到什么就转发什么——在一个主路由器本来就照顾不到的房间里，结果就是弱信号再被弱弱地转一次。
屋里正好还有一台闲置的 TP-Link 路由器，我们把它配成了卧室里的副路由器，回程走网线而不是走无线。台式机现在直接插在它上面，测速正常，房间同时也多了一份自己的无线覆盖。整个过程没有添置任何新设备，只是把家里已有的东西换了个更好的用法。
Wireless extender or a wired second router无线扩展器 vs 有线副路由器
| Wireless extender (what they had)无线扩展器（原本用的） | Wired second router (what we set up)有线副路由器（我们改成的） |
|---|
| How it reaches the main router它怎么连回主路由器 | Over the air, repeating the signal靠无线中继转发信号 | Over a cable靠一根网线 |
| Signal quality in the room房间里的信号质量 | Poor — only as good as what it receives差，取决于它自己收到的信号 | Independent of the main router's coverage不受主路由器覆盖影响 |
| Wired port for the desktop给台式机的有线口 | Not what it is for本来就不是干这个的 | Straight into the PC直接插到电脑上 |
| Extra hardware needed需要额外买东西吗 | The extender一台扩展器 | A spare router they already owned他们家里本来就有的备用路由器 |
| What it needs from the flat对房子的要求 | Nothing没有要求 | A cable run to the room需要一根网线走到房间 |
What to take from this one
这一单值得记住的几点
- A lit port proves the cable and the sockets, nothing more. Do not let it talk you out of suspecting the computer.
- Test with a device you trust. Plugging a known-good laptop into the same cable and port clears the entire network side in under a minute.
- Say what changed recently. "I reset the system yesterday" was the single most useful sentence of this visit.
- Download the network driver before you reset a PC, and keep it on a USB stick. A machine with no network cannot fetch its own network driver.
- Watch whether the symptom changes after each fix. Connecting and dropping is not the same failure as never connecting.
- A wired second router beats a wireless extender whenever you can get a cable to the room, and often the spare router is already in the cupboard.
- 口亮只能证明网线和两头的接口，别让这盏灯说服你放过电脑这一侧。
- 用一台你信得过的设备去测。把确定正常的笔记本插到同一根线、同一个口上，一分钟之内就能排除整个网络侧。
- 把最近改动过什么说出来。「我昨天刚重置了系统」是这次上门里最有用的一句话。
- 重装电脑之前先把网卡驱动下好存到 U 盘。没有网的机器，是没法自己去下载网卡驱动的。
- 每修一步都看症状有没有变。「连上又断」和「一直连不上」不是同一个故障。
- 只要能把网线走到房间，有线副路由器都比无线扩展器强，而那台备用路由器往往就在柜子里躺着。
Result最终结果
The desktop came back online over a wired connection after the network adapter driver was installed and the router was reset to clear the abnormal address allocation, and the bedroom now has a wired second router in place of the wireless extender — the PC plugged straight into it, with its own wireless coverage on top. About an hour and a half on site, with no new hardware bought.
装好网卡驱动、并重置路由器解决地址分配异常之后，台式机通过有线恢复正常上网；卧室里的无线扩展器也换成了有线回程的副路由器——电脑直接插在上面，房间还多了一份自己的无线覆盖。现场大约花了一个半小时，没有添置任何新设备。