Dodo 250M Fibre Kept Dropping Out in Chifley: Changing DNS Did Nothing, the Second Router Was Dialling PPPoE Too

Share house · ChifleyDodo 250M fibre6 people sharingRandom dropoutsChanging DNS did not helpSecond router misconfigured

The first message was a wall of symptoms: dropping out, devices that would not connect, slow speed tests, and a list of everything they had already tried — including changing the DNS servers, which is the advice you find everywhere online. Six people share this Chifley house on a Dodo 250Mbps fibre plan with PPPoE and a TP-Link router. It read like a complicated fault. On-site it took one pass of link-by-link testing, and the culprit was the second router.

Where the network was breaking · two routers, both dialling

Fibre / ONT

250M

→

Main router

PPPoE ok

→

Cable into LAN port

wrong

Bottleneck

→

Second router

dialling too

Bottleneck

→

6 people's devices

drop out

The main router dials PPPoE and hands out addresses for the whole house. The second router had never been reconfigured: it was still in router mode trying to dial PPPoE itself, and its uplink cable was plugged into a LAN port instead of the WAN port. That gives you two devices fighting over addressing on the same network — which shows up exactly as the housemates described: slow address assignment, devices that cannot connect, and connections that drop at random. No DNS setting can fix that.

Why changing DNS was never going to help

DNS is the phone book that turns a website name into an address. Changing it can help when pages are slow to start loading but the connection itself is solid.

These housemates were losing the connection entirely, and devices could not get on the network at all — that happens below DNS, at the addressing layer.
Generic online fixes assume your setup matches the writer's. They rarely mention how many routers you have, how they are cabled, or what mode they are in.
When several people share one house, one wrongly configured box affects everybody, so the symptoms look random and impossible to pin down.

How we isolated it on-site

Wired into the main router and waited for the fault to appear

Slow to get an IP, speed itself normal

Plugged our own router and cable straight into the wall port

Line, cable and provider all ruled out

Reset the main router, kept WAN only, unplugged every LAN cable

Network stable with one router alone

Logged into the second router's admin page

Still set to PPPoE, cable in a LAN port

Reconfigured it, reconnected both, tested many devices

Still clean when we checked back an hour later

The method is boring on purpose: prove each link with gear you know is good, and change one variable at a time.

Wired straight into the main router and waited for the fault to reproduce — speed was fine, but getting an address took far too long.
Brought our own router and cable to the wall port to rule out the line, the cabling and the provider in one move.
Reset the main router and stripped it back to the WAN cable only. With everything else unplugged the network was stable — so the fault was downstream, in the house.
Logged into the second router and found it still in dial-up mode with its uplink in a LAN port.
Reconnected both and tested with many devices at once, then checked again an hour later.

A second router: router mode vs access point mode

	Router mode (what it was)	Access point mode (what it needed)
Dials PPPoE	Yes — a second dial-up on one line	No — the main router dials
Hands out addresses	Yes, competing with the main router	No, the main router does it
Uplink cable goes to	Was plugged into a LAN port	WAN port, or LAN-to-LAN in AP mode
What users see	Slow to connect, random dropouts	One stable network across the house

If your house has more than one router, this is the first thing to check.

Only one device on the network should dial the connection and hand out addresses. Everything else should be an access point.
A router that used to be someone's main router will still be in router mode when it is reused as a second one — nothing resets that for you.
Check which port the uplink cable is in before you blame the provider.
If you cannot find the fault after a couple of attempts, get someone to test it properly rather than losing weeks to guesswork.

Result

Root cause: the second router was still in router mode dialling PPPoE, with its uplink cable in a LAN port — two devices competing to run the same network. Neither Dodo, nor the fibre line, nor the DNS servers were involved. After reconfiguring it and reconnecting both routers, all six housemates' devices connected normally, and a follow-up an hour later found no recurrence.

Dodo guide NBN slow speed troubleshooting Why there is no internet and how to recover TP-Link routers What is FTTP fibre Maroubra service area

Dodo 250M Fibre Kept Dropping Out in Chifley: Changing DNS Did Nothing, the Second Router Was Dialling PPPoE Too

Why changing DNS was never going to help

How we isolated it on-site

A second router: router mode vs access point mode

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