Degradation since 31/12/24 when 2 Openreach vans visited neighbour

[#1]

Since December 31, 2024, I've noticed a significant drop in the consistency of my Full Fibre 900 speed.

Two Openreach vans were visiting a neighbour's house right when the issue began, which seems too convenient to be a coincidence.

I've attached screenshots from Grafana, which monitors my connection every 15 minutes using speedtest. I've already tried rebooting the router and ONT, but the degradation persists. What would be the best way to get this investigated?

[#2]

Previous to 31/12/24, download speeds were consistently 935 Mb/s and upload 108 Mb/s, with occasional reductions, which is to be expected.

Since 31/12/24, download speed mostly hovers between 300 and 800, with very occasional 935s.

Upload seems to be unaffected and remains consistently 108.

Note these are on a wired connection, not wireless.

[#3]

@brocola Hi there, After our quick phonecall today and a lovely chat, we're going to monitor this issue over the next couple of days as the line tested fine. When I'm back in on Saturday ill be giving you another call to chase this up with you. 

As discussed aswell, keep an eye on this post as the superusers and other members of our community may be able to provide some further help in figuring out the issue. ☺️

[#4]

Thank you Joe, I really appreciate the call. Will see if I can setup a scheduled & logged trace route to monitor routes to somewhere like bbc.com and report back.

[#5]

@brocola Do you know what OR were doing at the neighbours? A very long shot, but if they were installing FTTP, it may be that they disturbed your connection on the CBT - unlikely, but possible.

[#6]

Surely a FTTP connection either works at full speed or doesn't work at all? A drop in measured speed would indicate congestion somewhere rather than a bad joint.

[#7]

I don't know, @corringham , but the coincidence of the OR visit and the degradation  needs to be taken into account. The obvious, from the graph provided, change to the OP's connection reliability, must have some cause.

I'm no expert, but graphs don't lie, and that one shows a pattern.

@brocola Are to on an underground or overhead feed?

[#8]

@jab1 but the graph isn't showing any connection unreliability, just a lower download speed. I would expect that either there is something else using bandwidth at the same time as the speed test is running, or there is congestion somewhere.

[#9]

Again, I agree with you, but the change in graphing immediately after the 'visit' is a coincidence? Sorry, but I don't believe  it.

[#10]

It is possible that the neighbour is a high bandwidth user. FTTP GPON is a contended service - I believe up to 32 connections share a 2.4Gbps down 1.2Gbps up fibre connection. The cumulative max speed of all the connections may be above the 2.5Gbps available - typically most connections will be using only a fraction of their maximum, so everyone gets their expected speed.

However, if several connections are attempting to use their max at the same time (e.g. running repeated speed tests) then there may be congestion and the achieved speed will be lower. 

[#11]

I know all that, but the neighbour would have to be a consistently high user to have that kind of effect - IMO. However, as we don't even know what OR were doing, this is all conjecture - I was only throwing out a (potentially wrong) idea.

We need more from the OP.

[#12]

@jab1 we're on an underground feed.

I believe the OR visit was for a fibre installation at a neighbour's house, saw one of the guys working with a coil of fibre...

The timing is suspicious. The degradation in the graph correlates within a few minutes of the first van arriving on my timestamped CCTV footage. 

I'm not aware of any internal network changes on that day which would cause persistent and ongoing increased bandwidth usage. I was busy preparing and cooking a rib of beef at the time, and I'm the only one who would have made any changes.

[#13]

Cheers, @brocola . Do you know the neighbour well enough to ask yhem to confirm it was an FTTP installation, and if they are very heavy users? Mind you, if the problem arose so soon after the first van arrived, it does seem likely that whatever they did is maybe the cause.

I don't know - I'm not a telecoms engineer.

[#14]

Zoomed in graph attached of last 24 hours. The degradation doesn't seem to be limited to times where one might except high usage. Unless someone was running a server hosting something like linux isos for download worldwide.

[#15]

Screenshot of comparable 24 hour period from a 4th December 2024.

I'm not exactly sure which neighbour was being visited. At this stage, would prefer not to be knocking doors to find out.