Case Studies案例研究 / Latest Case最新案例 Superloop Gigabit Plan Stuck at 100 Mbps: the Router's LAN Port Was the Bottleneck (Waterloo)
Superloop千兆套餐却只有100兆：瓶颈是路由器的百兆LAN口（Waterloo）
Student · Waterloo学生 · WaterlooSuperloop 1000MSuperloop 千兆Stuck at 100 Mbps卡在100兆Fast Ethernet LAN port百兆LAN口Second-hand router二手路由器Fixed to ~920M wired有线修到~920兆
A student in Waterloo had signed up for a Superloop gigabit (1000Mbps) plan, but every speed test topped out around 100Mbps. They assumed the provider was throttling them. We brought our own router and cables to test link by link on-site — and the plan turned out to be fine. The bottleneck was a second-hand router whose LAN port (and cable) only ran at 100 Mbps.
一位住在 Waterloo 的同学开通了 Superloop 的千兆（1000兆）套餐，但每次测速都只有 100 兆左右，一度以为是运营商限速。我们自带路由器和网线上门、逐环节对比测试——结果套餐完全没问题。真正的瓶颈是一台二手路由器：它的 LAN 口（和网线）只有百兆。
Wired speed · before vs after有线测速 · 处理前 vs 处理后
9×faster on the same Superloop gigabit line — nothing changed on the plan, only the router and the port.在同一条 Superloop 千兆线路上快了约 9 倍——套餐一点没动，只换了路由器和接口。
The trap: a gigabit plan does not mean gigabit at your device
误区：千兆套餐 ≠ 千兆到你的设备
Where the speed was lost · the weakest link速度卡在哪 · 最弱的一环
A connection is only as fast as its slowest link. The plan, the modem and the modem-to-router cable were all gigabit — but this second-hand router's LAN port maxed out at 100 Mbps (Fast Ethernet), so every device behind it was capped at ~100. A 100M patch cable would do the same thing.一条链路的速度 = 最慢那一环。套餐、光猫、光猫到路由器的网线都是千兆——但这台二手路由器的 LAN 口最高只有 100 兆（百兆 Fast Ethernet），于是它后面所有设备都被卡在 ~100。一根百兆网线也会造成同样的结果。
People see “1000Mbps” on the plan and assume every device gets it. But the speed you actually get is set by the slowest link in the chain — the line, the modem, every cable, the router’s ports, and the device’s own network card. Here the Superloop line, the modem and the modem-to-router cable were all gigabit. The one weak link was the router: a second-hand unit bought on Xiaohongshu whose LAN port was 100M Fast Ethernet, paired with a 100M patch cable. No plan upgrade could ever get past that 100M ceiling.
很多人看到套餐写着 “1000兆” 就以为每台设备都能跑到。但你真正拿到的速度，取决于链路里最慢的一环——线路、光猫、每一段网线、路由器的接口、以及设备自己的网卡。这里 Superloop 线路、光猫、光猫到路由器的网线都是千兆，唯一的弱环是路由器：一台在小红书上买的二手机，LAN 口是百兆 Fast Ethernet，还配了根百兆网线。套餐升到再高，也过不了这个 100 兆的天花板。
How we isolated it on-site
现场怎么一步步定位
How we isolated it on-site现场怎么一步步定位
1
Wired laptop straight into the router笔记本网线直连路由器
LAN port tested ~100 MbpsLAN口测得 ~100 兆
2
Speed-tested WiFi on 2.4G and 5G2.4G 与 5G 分别测 WiFi
Both ~100 Mbps too两个频段也都 ~100 兆
3
Checked the modem-to-router cable检查光猫到路由器的网线
Cable was gigabit → router at fault网线是千兆 → 锁定路由器
4
Swapped in a gigabit-capable router换上我带的高性能路由器
Wired hit ~1000 Mbps有线冲到 ~1000 兆
5
Wired the bedroom port to the desk接通卧室网口到台式机
Bedroom wired ~920 Mbps卧室有线 ~920 兆
The method is simple: test each link with gear you know is good, and change one thing at a time.
- Wired a laptop straight into the router — still ~100M, so it was not just WiFi.
- Tested WiFi on both 2.4G and 5G — also ~100M, pointing away from the wireless side.
- Confirmed the modem-to-router cable was gigabit — so the line and cabling were fine, leaving the router.
- Swapped in our own gigabit-capable router — wired speed jumped to ~1000M, proving the old router was the cap.
- Wired the bedroom wall port to the desk and measured ~920M for a stable, low-latency connection.
方法很简单：用你确定没问题的设备逐环节测，每次只改一个变量。
- 笔记本网线直连路由器——依然 ~100 兆，说明不只是 WiFi 的问题。
- 2.4G 和 5G 都测——也都 ~100 兆，基本排除无线端。
- 确认光猫到路由器的网线是千兆——线路和布线没问题，问题指向路由器。
- 换上我们自带的千兆路由器——有线直接跳到 ~1000 兆，证明是老路由器在卡。
- 接通卧室墙口到台式机，实测 ~920 兆，稳定、低延迟。
100M port vs gigabit port: how to tell before you buy
百兆口 vs 千兆口：买之前怎么分
100M port vs gigabit port · how to tell百兆口 vs 千兆口 · 怎么分
| Fast Ethernet (100M)百兆口 (100M) | Gigabit (1000M)千兆口 (1000M) |
|---|
| Max speed最高速率 | 100 Mbps | 1000 Mbps |
| Standard标准 | 100BASE-TX | 1000BASE-T |
| Often on常见于 | Cheap / old / second-hand routers; old Cat5 cables便宜/老旧/二手路由器；老 Cat5 网线 | Modern routers; Cat5e / Cat6 cables现代路由器；Cat5e / Cat6 网线 |
| How to check怎么分 | Read the router’s spec sheet, look for “Gigabit” on the port silkscreen, or check the negotiated link speed in the router admin page. Test wired, not WiFi, to rule the port in or out.看路由器规格书、看接口旁丝印是否标 “Gigabit”，或在路由器后台看协商的连接速率。判断接口要用有线测、别用 WiFi。 |
This trap is common with cheap or second-hand routers. Before you buy, check the port speed — not just the WiFi standard.
- Read the spec sheet for “Gigabit” / 1000BASE-T LAN ports.
- Use Cat5e or Cat6 patch cables, not old Cat5.
- Always test wired (not WiFi) to prove whether a port is the limit.
这个坑在便宜或二手路由器上很常见。买之前先确认接口速率——不要只看 WiFi 标准。
- 看规格书是否为 “Gigabit” / 1000BASE-T 的 LAN 口。
- 网线用 Cat5e 或 Cat6，别用老的 Cat5。
- 判断接口是否卡速，一定要用有线测、而不是 WiFi。
Result最终结果
Root cause: the second-hand router’s 100M Fast Ethernet LAN port (and a 100M cable), not Superloop. On a gigabit-capable router the same line delivered ~920 Mbps wired to the desk — a 9× jump with no plan change.
根因：二手路由器的百兆 Fast Ethernet LAN 口（外加一根百兆网线），不是 Superloop。换成千兆路由器后，同一条线路有线到桌面 ~920 兆——套餐没动，速度提升约 9 倍。