Speed Decreasing (Decreased 30%)

[#1]

I have a fibre package and I live in a rural area so I am a long way (about a mile) from the cabinet. Originally I was getting a connection speed of about 12.5Mbit/s as reported by the router's and various online speed tests.

This winter there have been a number of intermittent disconnections during bad weather and power cuts. When the modem has reconnected, it has been reporting ever decreasing speeds. It is currently down to:

Downstream:	9.489 Mbps
Upstream:	1.149 Mbps

The upstream rate has also decreased from about 1.5Mbit/s originally. I have confirmed the reduction in performance with various online speed testers. This equates to a performance drop of over 30%.

My physical set-up has not changed. I have the original Plusnet router and the configuration has not changed.

I rely on this connection for work, and I am starting to struggle. If it gets any slower, I will need to choose an alternative.

Could this be a physical problem with the connection to the cabinet?

[#2]

@ijn667 

For Community members to be able to help, information from these sites, as screenshots, posted as pictures within the topic, not as attachments:-

BT Broadband Availability Checker (obscuring your phone number), where a landline phone is no longer supplied or known use the address version BT Broadband Address Availability (obscuring your address)

BTW Performance Tester - Over a wired (Ethernet) connection if at all possible, please report the 'ADDITIONAL DIAGNOSTICS'. This test is recommended to be performed with only one device connected.

Sight of the broadband connection status from your Hub (with the 'Username' obscured) would also be of help.

For the Hub One -

Navigate from the Home Screen to Troubleshooting > Helpdesk

For the Hub Two -

Navigate from the Home Screen to Advanced Settings > Technical Log > Information

Where the phone line is still active, it may also be a good idea to report the results of a Quiet Line Test - dial 17070 option 2 from a (preferably corded) phone. After the confirmation of your phone number, there should be total silence apart from the regular 'Quiet Line Test' announcement. Any other noise - report a PHONE fault first.

If you are unsure about any of the above, please just ask - I am happy to help.

[#3]

[#4]

Looking at that, you have a couple of problems. I'm out for a couple of hours, but if no-one else responds, I'll comment when I return.

[#5]

I also tried the silent line test with a wired telephone. There was a very faint background hum.

[#6]

Thanks.

[#7]

@ijn667 your downstream noise margin is slightly elevated ( 8.7db ) which would indicate that the DSLAM has raised the target SNR from 6db to 9db to attempt to reduce errors. This will be the cause of the reduction in downstream speed. However your speed is above the handback threshold (showing as 6.3Mb) , so getting Openreach to investigate a possible line issue will be tricky.

edit : just seen your post

There was a very faint background hum.

It should be silent, I'd report a fault either using the textbot https://www.plus.net/help/report-a-problem/ or at

https://faults.plus.net

[#8]

I've reported the telephone faint background hub at faults.plus.net and linked to this discussion.

[#9]

@ijn667 - Hi, I have tested your phone line which tests fine and I've tested your broadband also tests fine. The sync rate is 9.5/1.1.

Looking at this solely as a broadband issue, it's performing above the sync rate we'd expected and likely causing the higher error rates causing the speed test loss of 30%. Eventually, the sync rate will reduce the sync rate still in line with your estimate of 8.4 and you will likely see a lesser % between the sync and the speed observed on the speed tester. I don't really have the justification to report this fault to Openreach at this stage. 

In terms of the hiss on the phone line, as the test isn't finding a fault, we need to go down the route of removing all equipment from the phone socket and trying another known working phone to confirm the slight hiss isn't relating to the handset itself.

[#10]

Thanks for looking into this.

Regarding the noise on the phone line, it's actually more like a faint mains hum than a hiss. I have tried plugging the phone directly into the wall socket, bypassing the splitter.

Regarding the broadband issue, I'll restate that the router's modem reported connecting at 12.5Mbit/s for over two years, having had the service since spring 2021. Online speed testers routinely told me I was getting over 1 megabyte per second download (1.2 to 1.3). It is only in the last 2-3 months that the connection rate has dropped. What is concerning is that it has continued to drop gradually since about December. A few weeks ago, the modem was reporting about 10.5Mbit/s.

Something has happened this winder to degrade the performance of the connection, and I now experience a 30% reduction in performance on what was already a pretty slow line.

I understand that the infrastructure is provided by BT, and so changing ISP will make no difference unless I opt for something completely different, such as satellite. I am not in a good location for mobile phone data. I don't get a signal at all here.

One potentially useful piece of information which BT may be interested in is that one of their cable connections may be under water. When this connection was installed, the engineer had to pump out a lot of water from the hole by the road containing the cabling. I believe moisture can affect the capacitance of the cables and thus the bandwidth.

[#11]

By the way, Plusnet customer service has always been very good. You replied very promptly. Thanks again.

[#12]

Your line attenuation implies a line length (by whatever route it takes) of about 2.6Km, over 1.5 miles. Nonetheless it "should" have a download speed of around 11mbps (you noted 10.5mbps which is consistent).

As noted above, your noise margin has been elevated from the normal 6db to around 9db which would explain the speed reduction. The question then is why and can anything be done about it?

[#13]

It sounds like I'll have to wait for it to get worse, below the threshold, to get BT Openreach to investigate.