Why is my 1 Gbps fibre only delivering 50 Mbps in Auckland?
Your router is the bottleneck, not the fibre. The ONT delivers 1 Gbps to your wall — but old WiFi routers, Cat5 (not Cat6) cabling, or APs running 2.4GHz cap throughput around 50-100 Mbps. Fix in order: upgrade to a WiFi 6 router ($150-$300), wire critical devices to Cat6 ($480 install), and add a 5GHz/6GHz-capable AP if your house is over 120m². See WiFi install pricing.
Why your 1 Gbps fibre plan is delivering 50 Mbps — and what to fix in 2026
You signed up for 1,000 Mbps fibre. Your speed test says 50. Your Zoom calls drop. Your kids complain. Here’s exactly why — and the four fixes ranked by cost, in order of biggest payback.
The short answer: 9 times out of 10, your fibre is fine. The bottleneck is between your ISP modem and the device you’re testing on. Most often: the WiFi distribution. Sometimes: the cabling between rooms. Almost never: your ISP.
How fibre actually reaches your laptop
When Chorus or 2degrees turns on your fibre plan, here’s the chain:
- Fibre comes into the house at the ONT (the white box on the wall, often in the garage or laundry).
- An Ethernet cable runs from the ONT to your modem/router. Almost always Cat5e or Cat6.
- The modem broadcasts WiFi. Or sends data via Ethernet to other rooms.
- Your laptop / phone / TV receives. Usually via WiFi, sometimes via wall socket.
Each link in that chain has its own speed limit. The 1 Gbps you’re paying for is the speed of step 1 — fibre into the house. Steps 2, 3 and 4 each cap what you actually receive.
The four real bottlenecks (ranked by how often they cause the problem)
1. ISP router WiFi (causes ~70 % of slow-speed complaints)
The router your ISP gives you (a Vodafone Ultra Hub, Spark Smart Modem, 2degrees Smart Modem, etc.) is designed to be cheap, not strong. Its WiFi covers one floor of an average NZ home, struggles through internal walls, and tops out at around 100–300 Mbps even at close range — not 1,000.
Your fibre plan can deliver 1 Gbps. Your ISP’s router can’t broadcast 1 Gbps over WiFi. That’s the gap.
Symptom: Speed test on phone in same room as router = ~300 Mbps. Speed test in master bedroom = ~50 Mbps. Speed test plugged in via Ethernet = full 1 Gbps.
Fix: 2–4 ceiling-mounted access points (Ubiquiti UniFi, Aruba, TP-Link Omada) with Cat6 cable backhaul to each one. About $1,200–1,800 fitted for a 3-4 bedroom home. Solves the problem in one day.
2. Old Cat5 or Cat5e cabling between rooms (causes ~15 %)
If your home was built before 2010, the data cabling in the walls is likely Cat5e — rated for 1 Gbps but only at short distances and only if perfectly terminated. Cat5 (no “e”) caps at 100 Mbps regardless of your fibre plan.
Symptom: Even plugged in via Ethernet, you only get 100 Mbps in the bedroom or office.
Fix: Re-cable with Cat6 or Cat6A. About $480–1,200 fitted for a typical home. Future-proofs you for 10 Gbps fibre when it arrives.
3. Old Ethernet cable to the modem (causes ~10 %)
The cable from the ONT to your modem might be Cat5e from 2014. Replace it with a 1-metre Cat6 cable from any electronics store (~$15). 30-second fix.
Symptom: Speed plugged in via Ethernet to the modem doesn’t exceed 300–500 Mbps.
4. Your laptop / device (causes ~5 %)
An older laptop with WiFi 4 or WiFi 5 can’t actually receive 1 Gbps over WiFi. WiFi 6 (802.11ax) hardware is required.
Test: Plug a recent laptop into the modem via Ethernet cable. If it gets 900+ Mbps wired but only 200 over WiFi, the device is the limit.
Quick diagnostic — do this before booking anyone
- Plug a laptop into your modem via Ethernet. Run fast.com.
- If you get 900+ Mbps wired: your fibre is fine. The problem is WiFi or in-wall cabling. Skip to fix #1.
- If you get 300–700 Mbps wired: the cable from ONT to modem is old. Skip to fix #3.
- If you get under 300 Mbps wired: ring your ISP. Likely a fibre fault or wrong plan.
What does it cost to fix, ranked by payback
| Fix | Typical Auckland cost | Solves it in | Lifetime |
|---|---|---|---|
| Replace ONT-to-modem cable (Cat6, 1m) | $15 DIY | 30 sec | 10+ years |
| Whole-home mesh WiFi with Cat6 backhaul (3 APs) | $1,200–1,800 fitted | 1 day | 7+ years |
| Re-cable home with Cat6/6A (4 outlets) | $480–1,200 fitted | 1 day | 15+ years |
| New laptop with WiFi 6 | $1,500+ | 10 min | 4–6 years |
The Auckland-specific bit
Auckland homes built before 2010 almost universally have Cat5e in-wall cabling at best. Hobsonville Point and other newer developments tend to have Cat6 pre-wired. If you’re renovating or moving into an older home, this is the moment to upgrade — opening up the walls for any reason makes the cabling job 30–50 % cheaper than retro-fitting later.
If you want a free 30-minute survey of your home, including a WiFi heat-map, we walk through the property and show you exactly which fix would solve YOUR problem — not the generic answer.
Want a real diagnosis (not guesswork)?
Free Auckland site visit. We bring the WiFi heat-map tool, plug into your modem, and tell you in 30 minutes exactly which fix you actually need. Fixed-price written quote in 24 hours. Same day or your call-out is free.
Book My Free Site Visit →Common questions
I have 4G/5G mobile broadband, not fibre. Does this still apply?
The bottleneck logic is the same, but the fibre-specific fixes don’t apply. For 4G/5G the most common bottleneck is signal strength to the router itself.
What about Mesh kits like eero or Google Nest from Bunnings?
They use wireless mesh-relay between units — that halves throughput per hop. Better than nothing, but for full fibre speed you need wired backhaul (Cat6 cable to each AP). Pro mesh systems cost slightly more but deliver true gigabit at every AP.
How long does the ONT-to-modem cable replacement take?
30 seconds. Buy a 1m Cat6 patch cable, unplug the old one, plug in the new one. The most under-rated DIY fix in this whole list.
Take the next step
If your slow fibre is a true fault (not just the router), our OTDR diagnostic locates it within 1 metre.
Often the real fix is proper data cabling in Auckland.
Before you accept any cabling quote: get the 8-Question Cabling Quote Comparison (free PDF)
The 8 questions Auckland homeowners and business owners ask before saying yes to a cabling quote — so you know what “good” looks like, what cowboys leave out, and don’t overpay. Or skip ahead and book a free on-site inspection from a Fluke-certified Auckland installer.