Case Studies案例研究 / Latest Case最新案例 The WiFi Disappeared Every Time a Download Started: Six Months of Dropouts Traced to a Failed ASUS RT-AX59U (Lidcombe)
一下载东西WiFi就消失：断了半年的网，最后查出是ASUS RT-AX59U路由器本身坏了（Lidcombe）
On-site · Lidcombe上门 · LidcombeOpticomm fibreOpticomm光纤25 Mbps plan25兆套餐ASUS RT-AX59UASUS RT-AX59UWiFi vanishes on download一下载WiFi就消失Router hardware failure路由器硬件故障
Two details made this one unusual. The WiFi did not just stop working — the network name disappeared from the list entirely. And it happened most reliably the moment a download started. The router was near new, its settings were normal, and it had already been reset. That combination points somewhere most people never look.
这一单有两个细节不太寻常。WiFi 不是「连着但没网」，而是名字直接从列表里消失；而且它最容易在开始下载东西的那一刻发生。路由器几乎是新的，后台配置一切正常，客户自己也已经 reset 过。这几点凑在一起，指向的是大多数人从来不会去看的那个方向。
Why "the WiFi disappears" is different from "the WiFi has no internet"
「WiFi消失」和「WiFi没网」是两回事
People describe both as the WiFi dropping out, and they are not the same fault at all.
If the network name is still in your list and you are connected to it but nothing loads, the wireless side is alive and the problem is somewhere between the router and the internet. If the network name vanishes from the list, the wireless radio itself has stopped broadcasting. Everything that happens after that first observation depends on which of the two you actually have. On this job it was the second one, and that is what moved a hardware failure to the top of the list rather than the bottom.
这两种情况大家都会说成「WiFi断了」，但它们根本不是同一个故障。
如果网络名字还在列表里、你也连着，只是什么都打不开，那说明无线这一侧是活的，问题出在路由器到互联网之间的某一段；而如果网络名字直接从列表里消失，那是无线本身已经不再广播了。第一步观察到的是哪一种，决定了后面所有动作。这一单是第二种，也正是这一点，把「硬件故障」从排查清单的最后一位提到了最前面。
A configuration problem or a dead router?是配置问题，还是路由器坏了？
| Usually a configuration or service issue通常是配置或服务侧问题 | What we found here这一单的实际情况 |
|---|
| What the WiFi doesWiFi的表现 | Stays visible, just has no internet名字还在，只是没有网 | Network name disappears completely网络名字整个消失 |
| Admin settings后台配置 | Something is wrong in there里面总能找到不对的地方 | Everything normal一切正常 |
| After a resetreset之后 | Usually improves or changes通常会改善或有变化 | Fault came back unchanged故障原样复现 |
| Under load, e.g. a download有负载时，比如开始下载 | Slows down but stays connected会变慢，但连接还在 | Drops out entirely直接断开 |
| Swapping in another router换一台路由器测试 | Same fault follows the line同样的故障跟着线路走 | Fault does not follow — unit is dead故障没有跟过来，说明是设备坏了 |
Which link was actually failing
真正出问题的是哪一环
Which link was actually failing真正出问题的是哪一环
Opticomm fibre to the property到住处的Opticomm光纤
fine / 正常
→
25 Mbps plan25兆宽带套餐
fine / 正常
→
ASUS RT-AX59UASUS RT-AX59U路由器
drops / 掉线
Faulty unit设备故障
→
Phones and laptop手机与笔记本
network vanishes / 网络消失
Everything on the service side was doing its job. The settings inside the router were normal too, which is what makes this class of fault so easy to misdiagnose — there is nothing to find in the configuration, so people keep looking at the provider. The failure was in the box itself, and the only way to prove that is to put a different box on the same line and watch the symptom fail to follow it.服务这一侧的每一段都在正常工作，路由器后台的配置也正常——这正是这类故障特别容易被误判的原因：配置里根本找不到问题，于是大家就一直往运营商身上想。故障出在那个盒子本身，而唯一能证明这件事的办法，就是在同一条线上换一个盒子，然后看症状会不会跟着走。
Why we waited on site instead of asking questions
为什么在现场干等，而不是继续问
The fault had been going on for around six months. By the time we arrived, the customer had stopped noticing exactly when it happened — early on they were not using the connection much, so the original pattern could not be reconstructed from memory.
Reported history is useful, but it is not evidence. So we stayed and waited until the fault reproduced itself in front of us. That one observation is worth more than any amount of description, because it fixes what the symptom actually is, and it gives you something you can retest against later. Without it, you are fixing a story rather than a fault.
这个故障已经持续了大约半年。等我们到的时候，客户其实已经说不清楚它具体什么时候发作了——早期他用网不多，原始的发生规律没法靠回忆还原。
客户描述的故障史有参考价值，但它不是证据。所以我们留在现场等，一直等到故障在我们眼前自己复现。这一次亲眼观察，比任何描述都值钱：它确定了症状究竟是什么样子，也给了你之后可以对照复测的标准。没有这一步，你修的是一个故事，不是一个故障。
How we isolated it on site现场怎么一步步定位
1
Went through the history — around six months of dropouts了解故障史——已经断断续续半年
Early occurrences not reproducible早期情况已无法还原
2
Waited on site until the fault reproduced itself在现场等待，直到故障复现
Confirmed with our own eyes亲眼确认症状
3
Checked the ASUS admin settings检查ASUS路由器后台配置
All normal, already reset once全部正常，客户已reset过
4
Swapped in a test router on the same line在同一条线上换一台测试路由器
Would not connect at first一开始无法直接上网
5
Customer called the provider to remotely reset the line由客户联系运营商远程重置线路
New router online新路由器联网成功
6
Ran the new router and watched for the same symptom用新路由器实测，观察症状是否复现
No dropouts — original unit faulty不再掉线，确认原路由器故障
The swap test, and the step that nearly blocked it
换机测试，以及中间差点卡住的那一步
Proving a router is dead means putting a different one on the same line. If the symptom stays with the line, the router was innocent; if the symptom disappears with the old unit, you have your answer.
The complication here was that the new router would not connect straight away after being configured. The customer called the provider, and the connection came up once it had been reset remotely on their side. That wait took a while, and it is worth planning for — if you are testing a spare router at home, expect that swapping hardware on some connections needs the provider to do something before the new unit is allowed online. Once it was up, we ran it and the dropouts did not return.
要证明一台路由器坏了，办法就是在同一条线上换另一台。如果症状留在线路上，那路由器是无辜的；如果症状跟着旧设备一起消失了，答案就出来了。
这一单的麻烦在于，新路由器配置好之后并不能直接上网。客户联系了运营商，对方在他们那一侧做了远程重置之后，网络才通。这个等待花了不少时间，也值得提前预留——如果你打算在家用备用路由器做这个测试，要有心理准备：在某些接入方式上，换硬件需要运营商先做点什么，新设备才被允许上线。接上之后我们实测了一段时间，掉线没有再出现。
What we would take from this one
这一单值得记住的几点
- Describe the symptom precisely. "The network name disappears" and "I am connected but nothing loads" send you down two completely different paths.
- A near-new router is not automatically a healthy router. Age makes hardware failure less likely, not impossible.
- Normal settings plus a reset that changed nothing is itself a finding. It moves hardware up your list instead of leaving it at the bottom.
- Wait for the fault if you can. One reproduction in front of you beats an hour of recalled history, especially after months of it.
- The swap test is the proof. Without a second router to compare against, most people end up blaming the provider — and the provider is often right to say their side is fine.
- Budget time for the provider step. Some connections need a remote reset before a replacement router is allowed online.
- 把症状描述准。「网络名字消失了」和「连着但打不开」，会把排查带向两条完全不同的路。
- 几乎全新的路由器不等于健康的路由器。新只是让硬件故障的概率变小，不是变成零。
- 「配置正常 + reset 之后毫无变化」本身就是一条线索，它会把硬件故障从清单末尾提到前面来。
- 有条件就等故障复现。在你面前发作一次，胜过一小时的回忆描述，尤其是已经持续了几个月的故障。
- 换机对比才是证据。手边没有第二台路由器可比，大多数人最后都会怪到运营商头上——而运营商说自己没问题，往往是对的。
- 给运营商那一步留出时间。有些接入方式下，换上的新路由器需要对方远程重置之后才被允许上线。
Result最终结果
With a test router on the same Opticomm line — online after the provider reset the connection remotely — the dropouts did not return, and downloads no longer made the WiFi vanish. That confirmed the original ASUS RT-AX59U had failed as hardware, despite being near new and having normal settings, and gave the customer a clear answer after around six months of intermittent dropouts.
在同一条 Opticomm 线路上换用测试路由器（由运营商远程重置线路后联网成功），掉线不再出现，下载时 WiFi 也不再消失。这确认了原来那台 ASUS RT-AX59U 属于硬件故障——尽管它几乎是新的、后台配置也一切正常。断断续续困扰了大约半年的问题，到这里终于有了明确结论。