Thank you to everyone who has messaged me. I hopefully have enough offers that I can run the additional checks that I'll need. For everyone is that is affected could I ask that you do raise the faults though the normal Technical Support channels if you have not already done so?

Regards,
Brandon.

Do you know if the originally supplied Fritzbox received a firmware update coincidental with the reduced downstream throughput.

I ask because by default these updates are enabled by and supplied from the manufacturer, though I think you can change the settings for busy times or notify-only or not at all.

It's possible that a later firmware combined with migrated config could result in some built-in QoS being active, which could favour low latency over sustained download throughput for example.

With asymmetric connections and a sequential test, during the upload test there is often plenty bandwidth for the ACKs (returning downstream) such that QoS does not need to kick in.

Otherwise I'd wonder if it was something else affecting PPPoE hardware acceleration (as a computer doing the PPPoE itself generally has more than enough CPU to handle it purely in software while a low power appliance relies on some kind assistance - may be called fast path or offload processing for example.

In my case, the slow speeds persist even when I've plugged a laptop into the ONT directly (bypassing the router)

Hi, no, there had been no FritzBox update, my router was at 7.29 (since Nov 2021), and the loan Fritz had same version. I also tried 7.30 beta, and that was exactly the same.

You are correct that boxes like my Time Capsule don't have enough horsepower to do 1Gb routing, but equally the problem is not that simple. It appears that most routers show packet loss over my connection (Time capsule and direct PPPOE seem much better for some as yet undiscovered reason). Zen are coming to me to run a line test tomorrow, so let's see what that shows.

I suspect that the router issue I'm seeing is somehow a symptom of the problem rather than the cause, it's just too incredible that 3 different routers are similarly faulty, and in the case of mine that it stopped working properly at EXACTLY the same time as my GEA migration?

Is/are any of your LAN cables one that was in use before the migration? If so, replace it with a brand new one. If you don't know which, replace all.

Also check all ethernet sockets for contamination including the ONT, before inserting a new cable. Air-blower clean perhaps. Similarly check and clean the plugs on the cables.

It does sound very much like a cabling fault to me.

Well this could be fun.

Tomorrow morning a Zen network engineer and an Openreach engineer are both going to be here.

Best get the kettle on. Also popcorn? 😁

Sorry, not cables!

Plug same cable into router that I use into the ONT, and no cables have changed in any case. I repeat !!! ALL this only occurred simultaneously with my GEA migration..... I changed no cables during that time, nor any of my equipment.

As I say on another post, it strongly seems like the 'router issue' is a red-herring, and is simply a symptom rather than the cause.

What the cause is? I'll publish as soon as I know, Zen engineer coming here tomorrow, don't think they'd do that if they suspected cabling! Or that 3 different routers suddenly fail in the same way !

In reply to a post by FakeJake:

Well this could be fun.

Tomorrow morning a Zen network engineer and an Openreach engineer are both going to be here.

Best get the kettle on. Also popcorn? 😁

I hope the three of you can work it out

It took a bit of pushing by those posting in this thread but Zen do now seem to be taking the GEA migration issue seriously so fingers crossed for a resolution or at least a plan of how too.

It's disappointing because this is really the sort of thing they should have been able to pick up on, just looking at the utilisation of the customer circuits before and after the migration would have shown that there was a problem.