Paying for a fast plan in a shiny CBD or Zetland tower and getting a fraction of it? If your building is FTTB — fibre to the building — the fibre stops in the basement, and the last stretch to your unit runs over the building's old telephone copper. That last stretch is where your speed lives or dies. Here's how it works, what's fixable from inside your apartment, and what genuinely isn't.
住在光鲜的 CBD 或 Zetland 高层里，花着高速套餐的钱，网速却只有零头？如果你的楼是 FTTB（光纤到楼），光纤只到地下室，从机房到你家这段走的是楼里的老电话铜线。你的网速就成败在这一段上。这篇讲清它的原理、哪些能在你家里修好、哪些真的修不了。
In an FTTB building, NBN fibre terminates at equipment in the comms room (usually the basement). From there, each apartment connects over the building's existing copper phone pairs using VDSL2. Copper performance collapses with distance and cable quality: a unit close to the comms room might sync near plan speed, while an identical plan on the 30th floor of the same building syncs at half of it. Same ISP, same plan, different physics.
FTTB 楼里，NBN 光纤终止在弱电机房（通常在地下室）的设备上。从那里到每套公寓，走的是楼里原有的电话铜线对，用 VDSL2 传输。铜线的性能随距离和线况急剧下降：离机房近的单元可能接近满速同步，同一栋楼 30 层的同款套餐可能只有一半。同一家运营商、同一个套餐，不同的物理规律。
This is why your neighbour's speed test proves nothing about yours, and why an ISP's "up to" speed means little in an FTTB tower. The number that matters is your line's sync rate — what the copper between the basement and your wall socket can physically carry.
所以邻居的测速对你毫无参考意义，运营商说的「最高可达」在 FTTB 高层里也没什么用。真正重要的数字是你线路的同步速率 — 地下室到你家墙口之间那段铜线物理上能跑多少。
The wrong socket. Many units have several phone sockets but only one is actually wired to the building riser — the rest are dead or daisy-chained extensions that wreck VDSL. Finding and using the primary socket is the single most common FTTB fix we make.
插错了墙口。很多单元有好几个电话口，但只有一个真正连着楼宇主线 — 其余是死口或串接的分机线，对 VDSL 是灾难。找到并使用主墙口，是我们做得最多的 FTTB 修复。
A non-VDSL modem. FTTB needs a VDSL2-capable modem-router. Plenty of routers people bring or buy are Ethernet-WAN only — perfect for FTTP, useless plugged into an FTTB phone socket.
不支持 VDSL 的设备。FTTB 需要支持 VDSL2 的 modem-router。很多人带来或买的路由器只有以太网 WAN 口 — 用在 FTTP 完美，插在 FTTB 电话口上毫无作用。
In-unit wiring faults. Corroded sockets, flattened cables under carpet, previous tenants' DIY splices — all destroy sync rate. Repairs here legally need an ACMA-registered cabler; ours are partners we bring in.
室内接线故障。氧化的墙口、被地毯压扁的线、前租客的野路子接线 — 都会摧毁同步速率。这里的维修依法需要 ACMA 注册布线技师；我们有合作的持证技师。
WiFi taking the blame. In dense towers, interference is savage. We regularly find the FTTB line syncing fine while WiFi delivers a third of it to the sofa. Cable-test before blaming the building.
WiFi 背了锅。高密度楼里干扰非常凶猛。我们经常发现 FTTB 线路同步正常，WiFi 却只把三分之一送到沙发上。怪楼之前先用有线测。
A plan faster than the line. If your copper syncs at 60Mbps, a 100Mbps plan burns money every month. Downgrading to what the line actually carries is sometimes the honest fix — we'll tell you when it is.
套餐超过了线路上限。如果铜线只能同步 60Mbps，100Mbps 套餐就是每月白烧钱。降到线路真实能跑的档位，有时才是诚实的解决方案 — 该降的时候我们会直说。
The building's riser copper and comms-room equipment belong to the building and NBN. If your line tests clean to the wall socket but syncs terribly, the issue is upstream: degraded riser pairs, a congested or faulty DSLAM, or building wiring that needs strata attention. You can't fix it — but you can prove it. An independent sync-rate report at your socket, in writing, is what moves a strata manager or forces your ISP to lodge it with NBN Co. We've done exactly this for buildings like World Square when a whole line showed no data signal.
楼宇主线铜缆和机房设备属于大楼和 NBN。如果测到你家墙口线路干净、同步却很差，问题就在上游：主线铜对老化、DSLAM 拥塞或故障、或需要物业处理的楼宇布线。你修不了 — 但你可以证明它。一份写成书面的、在你家墙口实测的独立同步速率报告，才能推动物业经理行动、或逼运营商向 NBN Co 报修。World Square 那单整条线路无数据信号时，我们做的正是这件事。
Long-term, some buildings qualify for upgrades (including FTTP upgrade programs). Whether yours does depends on address and program status — we check this for clients rather than guessing, since eligibility changes.
长期来看，部分楼宇符合升级条件（包括 FTTP 升级计划）。你们楼是否符合取决于地址和计划状态 — 资格会变，我们为客户实查而不是猜。
A CBD tower line with nothing on it — isolated to the building side, escalated with evidence.
CBD 高层线路完全无信号 — 定位到楼宇侧，附证据上报。
Read case →查看案例 →Right socket found, VDSL modem configured, tested before unpacking finished.
找对墙口、配好 VDSL 光猫，行李没拆完就测试交付。
Read case →查看案例 →Tell us your address and we'll check — or look at your setup: if your modem plugs into a phone-style wall socket and you live in an apartment block, FTTB (or FTTN) is likely. Full connection-type guide linked.
把地址发给我们帮你查 — 或看你的设备：如果光猫插的是电话样式的墙口、你又住公寓楼，多半是 FTTB（或 FTTN）。接入类型完整指南见链接。
Full guide →完整指南 →Different copper pair, different distance to the comms room, different in-unit wiring. Copper is individual — your line's sync rate is yours alone, which is why per-unit testing matters.
不同的铜线对、到机房不同的距离、不同的室内接线。铜线是「一户一命」— 你的同步速率只属于你家，所以必须按户实测。
Often yes: right socket, VDSL-capable modem, clean in-unit wiring and honest plan sizing regularly recover 30–50% of lost speed. Beyond the socket, it's evidence and escalation — or a building upgrade.
常常可以：插对墙口、用支持 VDSL 的设备、修好室内接线、套餐选实在档位，经常能找回 30–50% 的损失。墙口之外就靠证据上报 — 或楼宇升级。
Inside your unit: yours (with a registered cabler for fixed wiring). Building riser and comms room: strata and NBN, moved by evidence. ISP network: the ISP. A proper diagnosis tells you which — so you push the right door.
你家单元内：你自己负责（固定布线需持证技师）。楼宇主线和机房：物业和 NBN，靠证据推动。运营商网络：运营商。一次到位的诊断告诉你该敲哪扇门。
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全悉尼当天上门、24 小时、中英双语。大多数消息几分钟内回复。
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