Case Studies案例研究 / Latest Case最新案例 Connected to Every WiFi and No Web Pages Anywhere: a Laptop That Brought Its Network Problem to Australia (Remote Video Session, Sydney)
每个WiFi都连得上，网页却哪儿都打不开：一台把网络故障带到澳洲的笔记本（线上视频指导，悉尼）
Remote video session线上视频指导Windows laptop brought from Hong Kong从香港带来的笔记本Hotel, campus and phone hotspot all affected酒店、学校、手机热点全都一样Messaging app worked, web pages did not社交软件能收，网页打不开Leftover network configuration残留的网络配置Device-side fault故障在设备侧
There is one symptom that settles the question of whether a network is at fault faster than any speed test: the same problem following you onto a completely different network. This laptop failed on the hotel WiFi, on the university network and on a phone hotspot — three networks with nothing in common except the machine plugged into them. At that point there is nothing left to blame but the laptop.
有一种症状，比任何测速都更快地告诉你「问题不在网络」：换到一条毫不相干的网络上，同样的毛病还在。这台笔记本在酒店 WiFi、学校网络、手机热点上全都一样——这三条网络之间唯一的共同点，就是接在上面的这台机器。到这一步，能怪的就只剩笔记本自己了。
Why "some things work" is the most misleading symptom of all
为什么「有些东西还能用」是最容易骗人的症状
The laptop still received messages in one app. That single fact is what kept this problem unsolved for so long, because it makes the machine look connected — and in the sense most people mean, it was.
Getting on a WiFi network and being able to open a web page are two different achievements with a lot of machinery in between: the network association, an address, name lookups, and the browser's own path out. An app that keeps a connection alive and a browser opening a fresh page do not lean on all of the same pieces, so it is entirely normal for one to survive while the other does not. When you see that split, do not conclude the network is fine. Conclude that the break is somewhere above the WiFi and below the browser — which, on a machine that fails everywhere, means inside the machine.
这台笔记本在某个社交软件里还能收到消息。就是这一条，把问题拖了这么久没解决——因为它让机器看起来是「连着网的」，而按大多数人对这个词的理解，它确实连着。
连上 WiFi 和能打开一个网页，是两件不同的事，中间还隔着一大堆环节：无线关联、拿到地址、域名解析、以及浏览器自己出去的那条路。一个长连接活着的 App，和一个要新开页面的浏览器，依赖的并不是完全相同的那几段，所以「一个还能用、另一个不行」完全正常。看到这种劈叉，别急着下结论说网络没问题，应该下的结论是：断点在 WiFi 之上、浏览器之下——而在一台走到哪儿都不行的机器上，这就意味着断点在机器里面。
Same laptop, three unrelated networks同一台笔记本，三条毫不相干的网络
Hotel WiFi酒店WiFi
no web pages / 打不开网页
→
University network学校网络
no web pages / 打不开网页
→
Phone hotspot手机热点
no web pages / 打不开网页
→
The laptop这台笔记本
the one thing in common / 唯一的共同点
Fault is here故障在这里
Networks fail all the time, but three networks run by three different organisations do not fail in the same way at the same time for one person. When the symptom travels with the device, the device is the fault. This test costs nothing, needs no tools, and should be the first thing anyone tries before spending an evening on the phone to a provider.网络当然会出问题，但三家不同机构各自运营的三条网络，不会在同一时间、对同一个人、以同样的方式一起出问题。症状跟着设备走，故障就在设备上。这个测试不花钱、不用工具，应该是所有人在花一个晚上打电话给运营商之前，最先做的一件事。
What we checked first, and why finding nothing was still progress
我们先查了什么，以及「什么都没查出来」为什么也是进展
Three checks came before anything else, and all three came back clean.
The network adapter was enabled and showed no fault in Windows, so the hardware and its driver were not the story — unlike a machine that has just been reinstalled, where a missing driver is the usual answer. The browser had no proxy configured, which rules out the single most common cause of "connected but no pages" on a laptop that has been used behind a different network in another country. And no accelerator or tunnelling software was running at the time.
Three clean results are not a dead end. Each one removes a whole family of explanations, and what was left after them was the narrow and much less obvious category this fault turned out to belong to: configuration left behind by software that is no longer there.
有三件事我们排在最前面查，而且三件全是「没问题」。
网卡在系统里是启用状态、没有报错，所以硬件和驱动这一层不是本案的答案——这一点和刚重装完系统的机器不同，那种情况缺驱动通常就是答案。浏览器没有设代理，而对一台在另一个国家、另一套网络环境下用了很久的笔记本来说，代理残留是「连着网却打不开页面」最常见的单一原因。当时也没有任何加速器或隧道类软件在运行。
三个「没问题」不是死胡同。每一个都砍掉了一整类解释，剩下的那一小块，恰恰就是这次故障所属的、不那么显眼的类别：软件已经不在了，它留下的配置还在。
How the video session went这次视频指导的顺序
1
Confirmed the symptom across networks先确认症状在几条网络上都一样
Hotel, campus, hotspot — all the same酒店、学校、热点，表现一致
2
Asked what had changed and where the machine came from问清楚机器的来历和改动过什么
Worked normally in Hong Kong在香港时使用正常
3
Checked the network adapter in Windows检查系统里的网卡状态
Enabled, no obvious fault已启用，未见明显异常
4
Checked the browser for a proxy setting检查浏览器是否设了代理
No proxy configured没有设置代理
5
Checked running processes for accelerator software检查进程里有没有加速器类软件
Nothing running当时没有在运行
6
Worked through command-line network resets逐条尝试命令行的网络重置
Standard commands did not clear it常规命令没能清掉
7
Repaired the leftover network configuration继续处理残留的网络配置
Web pages opened again网页恢复正常打开
8
Confirmed she could upload her files确认可以上传同步资料
Data off the old machine老机器上的资料拿了出来
Software leaves, its settings stay
软件走了，它改过的设置还留着
This is the part worth remembering, because it is not intuitive. A lot of networking software does its job by changing settings on the machine rather than by running quietly beside them. Uninstalling such a program removes the program. It does not always put back what the program changed.
The result is a laptop that has no suspicious software on it, passes every check you can think of, and still cannot open a page — on any network, anywhere in the world, because the broken piece is carried in the machine's own configuration. The standard command-line resets are the right first move here and often enough; on this machine they were not, and the leftover configuration needed working through further before pages came back.
If you are moving countries with a laptop that has ever had accelerator, VPN or tunnelling software on it, this is a category of problem to be aware of. It will not show up until you are somewhere new and cannot get online, which is the worst possible moment to meet it.
这一段最值得记住，因为它并不符合直觉。很多网络类软件干活的方式，是去改机器上的设置，而不是安安静静地在旁边跑着。卸载这类程序，卸掉的是程序本身，它改过的东西不一定会被放回去。
结果就是：一台笔记本上找不出任何可疑软件，你能想到的检查它全都通过，却还是打不开网页——在世界任何地方、任何一条网络上都打不开，因为坏掉的那一块是被它自己带在配置里的。常规的命令行重置是这里应该先做的一步，很多时候也够用；这台机器上没够，残留的配置还要继续往下处理，网页才恢复。
如果你要带着一台曾经装过加速器、VPN 或隧道类软件的笔记本出国，这类问题值得先知道一下。它平时不会露头，非要等你人在一个陌生地方、又连不上网的时候才出现，而那正是最不想遇到它的时刻。
Is it the network or is it the device?到底是网络的问题还是设备的问题？
| Network-side fault网络侧故障 | Device-side fault (this case)设备侧故障（本例） |
|---|
| On another network换一条网络试 | Problem goes away问题消失 | Problem follows you问题跟着走 |
| On another device换一台设备试 | Other devices fail too别的设备也一样不行 | Other devices are fine别的设备都正常 |
| Who can fix it谁能修 | Provider, building or router运营商、楼里线路或路由器 | Only the device itself只能在这台设备上修 |
| Calling the provider打电话给运营商 | Worth doing值得打 | Will not help帮不上忙 |
| Typical first clue最典型的第一条线索 | Everything in the house is affected家里所有设备都受影响 | One machine, everywhere it goes只有一台机器，走到哪儿都一样 |
The order that would have saved her the most time
如果重来一次，最省时间的顺序
- Try a completely different network first — a phone hotspot is enough. If the problem follows the device, stop investigating the network.
- Try a different device on the same network. If everything else is fine, you have confirmed it from the other direction in under a minute.
- Do not treat a working chat app as proof that the connection is healthy. It proves less than it looks.
- Say what the machine has been through. "It came from another country" and "it used to have accelerator software" are both diagnostic facts.
- Check the browser's proxy setting early. It is one setting, it takes ten seconds, and it explains a large share of these cases.
- If you are replacing the machine anyway, still get it back online first — getting the files off is much easier from a computer that works.
- 先换一条完全不相干的网络试，手机热点就够。问题跟着设备走，就别再查网络了。
- 在同一条网络上换一台设备试。别的设备都正常，一分钟之内你就从另一个方向确认了同一件事。
- 别把「聊天软件还能收消息」当成网络正常的证据，它能证明的比看上去少得多。
- 把这台机器的经历说出来。「从别的国家带过来的」「以前装过加速器」都是诊断信息。
- 浏览器的代理设置早点查。就一个开关，十秒钟，却能解释这类案例中相当大的一部分。
- 就算已经打算换新机器，也还是先把它弄回能上网的状态——从一台正常的电脑上导资料，比什么办法都省事。
Result最终结果
The laptop opened web pages normally again after the leftover network configuration on the machine was repaired during the video session, with no change to the network she was using. She was replacing the computer soon in any case, and the immediate goal — getting her files uploaded and synced off an ageing machine — was met the same session.
在这次视频指导中把机器上残留的网络配置处理掉之后，笔记本恢复了正常打开网页，所在的网络一点没动。她本来就准备换新电脑，而当下最要紧的目标——把这台老机器上的资料上传同步出去——当场就达成了。