The Case We Could Not Close: a Dead DSL Light, Two Providers Saying Everything Is Fine, and a Locked Comms Room (Telstra, Sydney City)

一个没能修好的case：DSL灯彻底不亮，两边都说服务正常，楼里机房进不去（Telstra，悉尼City）

Student · Sydney city学生 · 悉尼CityTelstraTelstraDSL phone-line connectionDSL电话线上网D-Link routerD-Link路由器DSL light never comes onDSL灯始终不亮Unresolved — options given未能解决，已给替代方案

Most case write-ups end with the connection coming back. This one does not, and it is worth publishing anyway. The internet had worked for months. One morning it was gone, the DSL light on the router was dead, and nothing in the flat had been touched. Another technician had already looked at it before we were called. We took it on knowing that, and by the end we had ruled out everything inside the apartment and still could not reach the one place the fault most likely sits.

大部分案例最后都是网通了。这一篇不是，但依然值得写出来。网络本来正常用了几个月，某天早上起来就没了，路由器上的 DSL 指示灯彻底不亮，而屋里什么都没动过。我们接手之前，另一位技术人员已经看过一轮、没能解决。我们是知道这一点才接的，最后把公寓内部能排的全排完了，却依然进不去那个最可能出问题的地方。

Where the fault has to be, once the flat is ruled out把屋内全部排除后，故障只可能在哪一段

Telstra serviceTelstra服务

reported fine / 称正常

→

NBN networkNBN网络

reported fine / 称正常

→

Building comms room → flat楼内机房到住户这一段

no access / 进不去

Most likely here最可能在这

→

Wall socket & router墙上接口与路由器

tested good / 测试正常

The router and the phone cable were both replaced with our own known-good units and the DSL light still would not come on, which takes the flat's own equipment out of the picture. The retail provider and the network operator each reported their side as healthy. That leaves the run between the building's comms room and the apartment — the one segment nobody would send a person to look at.路由器和电话线都换成了我们自带的、已知没问题的设备，DSL 灯依然不亮，屋内自有设备因此被排除。运营商和网络方各自都说自己这侧正常。剩下的就只有楼内机房到这套公寓之间的那一段线路——偏偏就是没有人愿意派人去看的那一段。

A light that never comes on is a different problem from a slow connection

灯根本不亮，和网速慢是两类完全不同的问题

On a phone-line connection the DSL light is the first handshake of the whole chain. It matters more than any speed test.

Solid DSL light means the line has synchronised. From there, problems are about settings, speed or the router.
No DSL light at all means nothing has synchronised. No amount of changing settings in the router will help, because the router has nothing to talk to.
An intermittent flash — here, once every few minutes and never solid — usually points at a physical path that is almost, but not quite, intact.
If the light stays dark after swapping the router and the cable, stop working inside the flat. The answer is outside it.

在电话线上网的环境里，DSL 灯是整条链路的第一次握手，它比任何测速都重要。

DSL 灯常亮，说明线路已经同步。从这里往后，问题才是设置、速度或路由器。
DSL 灯完全不亮，说明根本没有同步。这时在路由器后台改多少设置都没用，因为路由器压根没有对话的对象。
断续闪烁——本例是每隔几分钟闪一次、从不常亮——通常指向一条几乎接通、但又没完全接通的物理线路。
如果换过路由器和线之后灯还是不亮，就别在屋里继续折腾了，答案在屋外。

Two visits and two phone calls, in order

两次上门、两通电话，按顺序

Two visits and two phone calls, in order两次上门、两通电话，按顺序

Took the job knowing another technician had already tried and not solved it在知道已有另一位技术人员看过、且没解决的情况下接手

Symptom: DSL light never lights症状：DSL灯始终不亮

Called Telstra on the student's behalf and explained the symptom in detail代该同学致电 Telstra 客服，详细说明症状

Told their service is normal被告知运营商侧正常

Telstra arranged for NBN to check their side; called again the next day for the outcomeTelstra 安排 NBN 方面核查，次日再次致电确认结果

NBN also reported normalNBN 方面也表示正常

Swapped in a different router and a different phone cable of our own换上我们自带的另一台路由器和另一根电话线测试

DSL light still dark — flat gear ruled outDSL灯依旧不亮，屋内设备排除

Re-seated the wall socket connection and watched the router for several minutes把家里的接口线重新接好，盯着路由器观察数分钟

Light now blinks once every few minutes, never solid灯开始每隔几分钟闪一次，但从不常亮

Went to the building office with the student to ask about the comms room和该同学一起到物业办公室，询问能否进楼内机房

Only credentialed provider staff may enter只允许持证的运营商技术人员进入

The re-seating result is the most useful clue in the whole job, even though it did not fix anything.

Before re-seating, the light was completely dead. After, it flashed once every few minutes.
A change in behaviour from a purely physical action tells you the physical path is where the problem lives.
It also tells you the fault is unlikely to be a total break — something is getting through intermittently.
That is exactly the kind of fault a technician standing in the comms room can find quickly, which is why access mattered so much here.

重新接线之后的变化，是整单里最有价值的线索，尽管它并没有修好问题。

重新接之前，灯是彻底不亮的；重新接之后，变成每隔几分钟闪一下。
一个纯物理动作能让表现发生变化，就说明问题确实住在物理线路上。
它同时说明这多半不是完全断开——总有信号在断断续续地过来。
而这恰恰是技术人员站在机房里最容易快速定位的那类故障，所以能不能进机房，在这单里格外关键。

What was ruled out, and what was left

排除掉了什么，还剩下什么

What was ruled out, and what was left排除掉了什么，还剩下什么

	Status after testing测试后的结论	How we know依据
Router路由器	Ruled out已排除	A second, known-good router behaved identically换上另一台已知良好的路由器，表现完全一样
Phone cable电话线	Ruled out已排除	A replacement cable made no difference换新线之后没有任何变化
User configuration用户设置	Ruled out已排除	Nothing had been changed; the link never comes up at all什么都没改过，而且链路根本没建立起来
Retail provider运营商侧	Reported healthy对方称正常	Telstra support checked and confirmed on the callTelstra 客服在通话中核查并确认
Network operator网络方	Reported healthy对方称正常	NBN checked at Telstra's request and confirmedNBN 应 Telstra 要求核查后确认
Comms room to flat机房到住户这一段	Never inspected从未被检查过	Telstra would not send anyone; building manager would not let us inTelstra 不派人，物业也不让我们进机房

We would rather publish this than pretend every job ends well. If you are stuck in the same loop, here is what we told the student.

Get the elimination on record first: a different router and a different cable, both tested, both giving the same result. It makes every later conversation shorter.
When the provider and the network operator both say they are fine, ask specifically for a technician to attend the premises rather than another remote check.
If the building will only admit credentialed provider staff, that is worth raising with the provider directly — it is the reason the fault cannot be reached.
When the loop will not break, the goal shifts from fixing the fault to getting the person online: changing provider, moving, or arranging something with a neighbour are all worth weighing up.
None of those are ideal. They are, however, better than another month without internet while two companies point at each other.

与其假装每一单都圆满收场，我们宁愿把这篇写出来。如果你也卡在同样的循环里，下面是我们当时给该同学的建议。

先把排除结果落实：换过的路由器、换过的线，都测过、结果一致。这会让之后每一次沟通都短很多。
当运营商和网络方都说自己正常时，要明确要求派技术人员到现场，而不是再做一次远程核查。
如果楼里只允许持证的运营商人员进机房，这一点值得直接跟运营商讲清楚——它正是故障够不着的原因。
当循环打不破时，目标要从“修好故障”转成“先让人有网用”：换运营商、搬家、或者和邻居商量共用，都值得权衡。
这些方案都不理想。但都好过在两家公司互相指认的同时，再没网过一个月。

Result最终结果

Not resolved. The router, the phone cable and the user's settings were all eliminated with our own known-good equipment, and both Telstra and NBN reported their sides as healthy, which leaves the run between the building's comms room and the apartment as the most likely fault — supported by the DSL light starting to flash every few minutes after the wall connection was re-seated. Telstra would not dispatch a technician and the building manager would only admit credentialed provider staff to the comms room, so the fault could not be reached. The student was given the realistic alternatives: change provider, move, or share a connection with a neighbour.

未能解决。路由器、电话线和用户设置都已用我们自带的已知良好设备逐一排除，Telstra 与 NBN 也都称各自侧正常，因此最可能的故障点是楼内机房到这套公寓之间的那一段——把家里接口线重新接好后，DSL 灯开始每隔几分钟闪一次，也支持这个判断。但 Telstra 不派技术人员上门，物业又只允许持证的运营商人员进入机房，故障因此够不着。最后给该同学的是现实可行的替代方案：换运营商、搬家，或与邻居商量共用网络。

The Case We Could Not Close: a Dead DSL Light, Two Providers Saying Everything Is Fine, and a Locked Comms Room (Telstra, Sydney City)

一个没能修好的case：DSL灯彻底不亮，两边都说服务正常，楼里机房进不去（Telstra，悉尼City）

A light that never comes on is a different problem from a slow connection

灯根本不亮，和网速慢是两类完全不同的问题

Two visits and two phone calls, in order

两次上门、两通电话，按顺序

What was ruled out, and what was left

排除掉了什么，还剩下什么

Related

相关链接

Facing something similar?

遇到了类似的问题？