topic Re: Significant drop in speed in Full Fibre

Significant drop in speed

rockposer — Fri, 26 Dec 2025 19:58:42 GMT

I've had my Full Fibre 900 connection for 18 months. My average download speed has been between 830Mb and a little over 900MB with an uplload of around 110Mb.

These speeds have never changed, until coming up a month ago when the download dropped to jan avwerage of just over 500Mb. The upload hasn't changed.

I contacted Plusnet who informed me that because my 'guarenteed' speed is 500Mb and the y cannot see a fault then there isn't an issue.

The estimated speed on my connectino is stated at 900Mb and this has bee nso for as I said 18 months. It's a significant drop in speed now being around 500Mb instead!

As I use a 3rd party router, a Unifi Cloud Gateway, rather than Plusnet's unit I was told there's nothing they could do further apart from send me a Plusnet router so they could run some sort of diagnostics (no details given)

After waiting for over 2 weeks I had to chase to find it in fact had never been actioned. As it's now Christmas it will have to wait.

Any suggestions as to the reson for this drop in speed?

Re: Significant drop in speed

Ali_A — Sun, 28 Dec 2025 14:45:33 GMT

Hi @rockposer

There could be a range of factors that may affect your speed, however there are some questions to help try identify what could be the cause-

Which device are you using to perform the speed test? Are you connected vis Ethernet cable to the router?

Did powering your router off for 5 minutes and back on make any changes to your speed?

Have you tried resetting your router or trying an alternative one (while waiting for the one from PlusNet)?

Ali

Re: Significant drop in speed

rockposer — Sun, 28 Dec 2025 17:26:34 GMT

Yes, connected via Cat6 cabling.

The speed test is done directly on the router. Far more accurate than the website based ones.

Powering off / re-botting the router and the ONT has made no difference to the speed.

Yes I've used an alternate router with the same result.

No settings have been alrtered at my end since first getting full fibre. As I said, the speed has been consistantly up to just over 900 so this drop to 500 makes me think that someone has changed the settings on my account.

Re: Significant drop in speed

rockposer — Thu, 01 Jan 2026 12:49:09 GMT

Well the Plusnet router finally arrived in the post, but as if by a miracle, before I'd even opened it the download speed mysteriously went back up to what it had been. Maybe it was the work of the baby Jesus!

Re: Significant drop in speed

MichaelD — Thu, 01 Jan 2026 15:09:15 GMT

Thanks for the update @rockposer.

Hopefully it stays like that now for you, but if you notice it drop again, give the Plusnet router a try, and if it carries on with that installed, let our tech guides know.

Michael

Re: Significant drop in speed

rockposer — Wed, 28 Jan 2026 20:28:11 GMT

Fingers crossed I'll never have to use a Plusnet router. Vastly inferior.

Re: Significant drop in speed

Townman — Sat, 31 Jan 2026 11:54:16 GMT

@rockposer

Would be interesting to see what your ticket history shows (see the link below). This sounds like a provisioning / build issue. It is not unheard of for something to go wrong within BT's space ... to all intents and purposes, the service is built correctly but the configuration is not. A change from something to something different and back again has been known to rectify issues.

The last time this was discussed with the business, the cause remained unknown.