This topic

Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Tue, 11 Nov 2025 20:55:26 GMT

I was persuaded to switch our phone to digital, and ditch the copper.

The whole process was disjointed, and with problems, but that's another issue.

In addition, each and every person at BT, and their subcontractors said we'd get much faster broadband.

Note, we have rubbish mobile coverage , and that's why we kept our landline.

I used to use a third party modem on the copper line and I'd easily get better than 10% faster performance than the bt modem. Typically 48mbps.

It seems, as we have a landline we have to use the bt modem. Oh well, I thought it should be way faster on fibre.

Once FTTP was eventually, and now using the bt modem, not only is the modem slower, but also the fibre is slower. Yes, believe it or not, it is!

I called bt and after spending some time trying to speak with someone who knows what's going on, I was told I'm on a speed limited deal. I had no idea.

On copper, 50mbps is pretty good. On fibre it's slow. Worse now that I'm getting between 25mbps to 38mbps at the very best, with apparent dropouts at busy times.

I regret switching to digital so soon, and should have waited until there was no choice.

I don't know why it's now apparently slower. When running the bt test it shows no issues.

Apart from sticking with this until the contract ends, or upgrading, has anyone else experienced this degradation?

Thanks in advance.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

imjolly — Tue, 11 Nov 2025 21:04:35 GMT

Are you sure you have moved to FTTP as that will give maximum speed for whichever broadband package you are on. I would not expect you to have regular drop out of connection.

Just because you moved to digital voice does not mean you are now on FTTP as DV works perfectly on FTTC

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Tue, 11 Nov 2025 21:17:40 GMT

Thanks. Am I sure? Well, the engineers spent ages trying to feed the fibre to the house. That's as sure as I can be.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

imjolly — Tue, 11 Nov 2025 21:28:14 GMT

Well if on FTTP does the 3 lights on ONT remain green? As I said if on FTTP then you should get the max speed for your package. Have you tried factory resetting the hub and ensure the FTTP switch in settings is moved to on

What broadband package are you on?

What speed do you get if you run. Fast.com

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Tue, 11 Nov 2025 21:33:45 GMT

Thanks, I'll need to move some furniture to see the box on the wall. I'll look tomorrow.

I'm not keen on factory resetting the hub as I'll have to faff around with all the settings again. Eg, turning off the WiFi, and disabling the other WiFi bt put on there, along with sorting out a very long ethernet to the pc on another floor.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

imjolly — Tue, 11 Nov 2025 21:45:39 GMT

But what package are you on?

Try fast.com and see what speed you get. Should be using ethernet connection not wi-fi

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Tue, 11 Nov 2025 22:20:26 GMT

Fibre 1 package

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

WSH — Tue, 11 Nov 2025 22:32:08 GMT

Even though it’s being delivered via fibre, "Fibre 1" is the most basic of the old FTTC products. The top speed for that package is only 50Mb/s, if memory serves, irrespective of what it’s delivered over.

You really need to upgrade the package to a true full fibre one. “Full Fibre 150” is the most basic. With a bit of haggling, you should be able to get that for no more that £30 a month.

Edit: The drop outs suggest a fault, though. You'll still need to report that.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Tue, 11 Nov 2025 22:40:19 GMT

Thanks, understood. I'm not yet ready to haggle.
What I don't get is why it's now slower than the copper, even if the package is the same. I've checked and 25mbps is the minimum I should expect on this package. Remember, I said I was getting over 40mbps on copper, and it was rock solid, no dropouts.
I think you can understand why I'm not impressed.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

WSH — Tue, 11 Nov 2025 22:51:13 GMT

With fibre optic you should get the limit of the package you are paying for. It is not subject to vagaries like distance from the cabinet etc. Having just checked, Fibre 1 is 55Mb/s. That should be what you get every time, rock solid.

As I said, if it's dropping out there is a fault.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Tue, 11 Nov 2025 23:01:00 GMT

Unfortunately, as I said, the Fibre 1 has a minimum of 25mbps, so it's seems it's software control.

The line test on the router responds with no error/problems.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

WSH — Tue, 11 Nov 2025 23:06:56 GMT

The thing to remember with that line test is that if the fault is intermittent, and doesn't occur during the test, it thinks everything is fine.

It could be a screw up with the profile/settings etc. Either way, it'll still need reporting.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Tue, 11 Nov 2025 23:15:21 GMT

Thanks.
I think what i'll do is to buy another BT modem/router from ebay and set that to the factory default for the purposes of the fault-finding exercise. That way I won't need to mess about with my own configuration, and reconfiguration. I might need to borrow a laptop that has an ethernet port to save running cables to the next floor where the PC sits. Unless you know of an adaptor for a PC with ethernet to USB.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

licquorice — Wed, 12 Nov 2025 07:42:17 GMT

This doesn't make sense, full fibre is not rate adaptive like copper, you get the full speed all the time. The 25M you keep referring to is only relevant with copper.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

imjolly — Wed, 12 Nov 2025 07:53:32 GMT

@poshsimon

did you try running test of fast.com and see what speed you get?

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Wed, 12 Nov 2025 09:13:27 GMT

@licquorice The 25mb I mention is what it says on BT's site for Fibre 1. I agree, it doesn't make sense, and that's why i raised the question.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Wed, 12 Nov 2025 09:17:51 GMT

@imjolly Yes, but only on WiFi as I explained I don't have a PC anywhere near the modem/router. Currently, 41mbps, and last night 25mbps

Note: I do realise that WiFi may not be accurate for many reasons, but it's a helpful guide.

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

imjolly — Wed, 12 Nov 2025 09:25:35 GMT

Only real test is Ethernet bearing in mind speeds quoted by BT are connection speed not download speed to deviice

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

pddco — Wed, 12 Nov 2025 10:32:27 GMT

@poshsimon Rather than using fast.com, why not use the MyBT app on your phone.

Click on ‘Your Products’ then ‘Broadband’ then ‘Speedtest’.

That way you’ll check the speed to the hub and then the WiFi speed to your mobile.

That’s the easiest way to see if it’s a WiFi or a service issue. Provided the cat 5 cable (ideally one with 8 wires terminated at each end for greater than 100Mbps) to your PC is sound, it should match the speed to the hub. And likewise your WiFi connection through the mobile near the hub should match too..

If the hub speed is wrong then report it as a fault. And as has been said previously, check the ONT lights as well.

Why go through the palaver of sourcing another hub.. Just seems to be making life difficult….

Re: Fibre switch from copper, now getting slower speeds after digital switchover.

poshsimon — Wed, 12 Nov 2025 11:25:39 GMT

Thanks, I didn't know about the MyBT App. I'll give it a go.