Phones Joined the WiFi Instantly, the Desktop Just Spun Forever: a Misconfigured Second Router (Superloop 100M, Zetland)

手机秒连，台式机一直转圈：问题出在第二台路由器上（Superloop 100兆，Zetland）

Student · Zetland学生 · ZetlandSuperloop 100MSuperloop 100兆DSL connectionDSL接入Two routers两台路由器Phones fine, desktop cannot join手机正常，台式机连不上Gaming LAN port used启用游戏专用LAN口

This is one of those faults where the symptom points you at the wrong device. The desktop was the thing that would not connect, so the desktop looks like the problem. It was not. The problem was a second router sitting quietly in the living room, doing its job badly enough to affect one type of device and not another.

这是那种症状会把你指向错误设备的故障。连不上的是台式机，所以看起来问题在台式机身上。并不是。问题出在客厅里那台安静工作的第二台路由器上，它没配好，而这种没配好恰好只影响一类设备、不影响另一类。

The setup

基本情况

Location: Zetland. Provider: Superloop. Plan: 100 Mbps. Connection: DSL.
Two routers in the flat — a main unit that supports DSL and handles the dial-up, and a second ASUS connected to it by its WAN port, providing the WiFi everyone actually used.
Reported fault: phones and other mobile devices connected to the WiFi normally, but the desktop spun forever and never joined.
Handled as an on-site visit.

所在区域：Zetland。运营商：Superloop。套餐：100兆。接入方式：DSL。
家里用了两台路由器——主路由支持DSL、负责拨号，副路由是一台华硕，用WAN口直接连到主路由，作为大家日常使用的主WiFi。
反馈的故障：手机等移动设备可以正常连WiFi，但台式机连接时始终转圈圈，无法连接。
处理方式：线下上门。

How the flat was actually wired这套房子实际是怎么接的

Superloop DSL lineSuperloop DSL线路

100M plan / 100兆套餐

→

Main router (dial-up)主路由（负责拨号）

ok / 正常

→

Second ASUS via WAN port第二台华硕（WAN口接入）

misconfigured / 配置不当

Bottleneck瓶颈

→

Phones手机等移动设备

joined fine / 正常连上

→

Desktop台式机

spins, never joins / 一直转圈

Two routers in series is a normal arrangement: the first one dials the connection, the second provides the WiFi you actually use. But the second one has to be set up for that role. When it is not, address allocation can go wrong, and the failure often shows on one class of device while others look fine — which is exactly why people blame the computer.两台路由器串联是很常见的做法：第一台负责拨号，第二台提供你日常在用的WiFi。但第二台必须按这个角色去配置。没配对的时候，IP分配就可能出现异常，而且故障常常只在某一类设备上表现出来、别的设备看起来一切正常——这正是为什么大家会去怪那台电脑。

Reading the symptom correctly

怎么把症状读对

Why the phone was fine and the desktop was not为什么手机没事，台式机有事

	Phones and tablets手机与平板	Desktop台式机
Symptom表现	Joined the WiFi normally正常连上WiFi	Spun indefinitely, never joined一直转圈，始终连不上
What that tells you这说明什么	The radio and the SSID are working无线信号和WiFi名称本身是正常的	The problem is after association, not before问题出在连上之后的环节，不是之前
Common wrong conclusion常见的错误结论	——	The computer's network card is broken以为是电脑网卡坏了
Actual cause here本例真正的原因	——	Second router not configured for its role第二台路由器没有按它的角色配置好

The split between device types is the most useful clue in this fault, and it is worth understanding why.

If the WiFi name is visible and phones join it, the wireless side of the second router is working. That rules out a lot.
A device that associates and then hangs is usually stuck waiting for an address, not struggling with signal.
Which is why the natural conclusion — that the desktop's network card has failed — is usually wrong. The desktop is the messenger.
The first thing worth checking in any two-router household is whether the second router has actually been configured for the job it is doing.

不同类型设备表现不同，是这个故障里最有用的线索，值得说清楚为什么。

如果WiFi名称能搜到、手机也能连上，说明副路由的无线部分是正常工作的。这就排除了很多可能。
一台设备能关联上、然后卡住，通常是卡在等IP地址，而不是信号不够。
所以最自然的那个结论——台式机网卡坏了——通常是错的。台式机只是那个报信的。
凡是家里用了两台路由器，第一件值得检查的事，就是第二台是否真的按它承担的角色配置过。

What we did on site

现场处理过程

How it was isolated on site现场怎么一步步定位

Map the setup: which router does what先理清楚：两台路由器各自负责什么

Main = DSL dial-up, ASUS = daily WiFi主路由拨号，华硕做日常WiFi

Reproduce the fault with the desktop用台式机现场复现故障

Cannot join the ASUS network无法加入华硕的WiFi

Form the hypothesis: second router misconfigured形成初步判断：副路由未正确配置

Suspect address allocation怀疑IP分配异常

Factory-reset the ASUS把华硕路由器恢复出厂

Clean configuration回到干净配置

Relocate it from the living room to his bedroom把它从客厅移到该同学的房间

Closer to where he uses it离实际使用位置更近

Use its gaming LAN port, wired to the desktop用它的游戏专用LAN口有线连到台式机

Wired path for gaming打游戏走有线

Rejoin with the desktop and restore the old SSID再用台式机连接，并改回原来的WiFi名称

Joins normally正常连接加入

Moving the router was not part of the fault, but it was worth doing while we were there.

The ASUS has a dedicated gaming LAN port, and he games regularly, so putting it in his room let us wire the desktop directly to that port.
A router in the room he actually uses also gives him better wireless than one sitting in the living room.
The network name was set back to what it had been, so nobody in the flat had to re-enter credentials on every device.

移动路由器本身不是故障的一部分，但既然人在现场，就顺手做了。

这台华硕有专门的游戏LAN口，而该同学日常玩游戏，所以放到他房间后可以把台式机直接有线接到那个口上。
路由器放在他真正使用的房间里，无线体验也比放客厅好。
WiFi名称改回了原来的，这样家里其他人不用在每台设备上重新输入一遍。

If you have two routers at home

如果你家也有两台路由器

Frequent disconnections, or devices that cannot join at all, are a common sign that one of the routers is not correctly configured for its role.
Check that the second router is set up as the device that hands out addresses, or as one that deliberately does not — but not accidentally somewhere in between.
If only some devices are affected, that is a clue, not a coincidence. Note which ones work and which do not before you change anything.
A reset on the second router is a reasonable early step, as long as you know the connection details for the main one.

经常有设备断连、或者干脆连不上WiFi，是一个常见信号：说明其中一台路由器没有按角色正确配置。
确认第二台路由器要么明确负责分配地址、要么明确不负责——不要不小心停在中间那个状态。
如果只有部分设备受影响，那是线索，不是巧合。动手改之前，先记下哪些能用、哪些不能。
只要你知道主路由的联网信息，重置第二台路由器是一个合理的早期步骤。

Result最终结果

Root cause: the second ASUS router, connected to the main DSL router by its WAN port and serving as the household WiFi, had not been correctly configured for that role, causing address allocation to fail for the desktop while phones connected normally. We reset the ASUS, relocated it from the living room to his bedroom to make use of its dedicated gaming LAN port for a wired connection to the desktop, and restored the original network name. The desktop then joined the WiFi normally.

根因是那台用WAN口接在主DSL路由器后面、承担全屋WiFi的华硕副路由，没有按这个角色正确配置，导致IP分配异常——台式机因此连不上，而手机却一切正常。我们把这台华硕重置，从客厅移到该同学房间，利用它专门的游戏LAN口把台式机接成有线，并把WiFi名称改回原来的。之后台式机可以正常连接加入WiFi。