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[cbdeakin]

I noticed that when downloading files, my speed drops down to about nearly half, from ~50mbps down to ~27mbps. This generally only happens every 1-2 minutes  (usually) for a few seconds, but sometimes the speed drops multiple times.

Is this likely to be caused by the homeplugs in my home? There's one connected to the router and several others around the house. The homeplug next to the router has VDSL - powerline avoidance mode on (I forget the exact name), which limits it to SISO speeds.

I noticed that when I enable bandwidth control on my router and select DSL for the connection type, it limites the speed to about 40mbps, but the speed is fairly constant (between 42-38mbps).  If I choose VDSL instead, the max download speed is higher, but it drops every couple of minutes.

Does selecting the DSL connection type somehow limit the FTTC connection to DSL frequencies only? And therefore, avoid the well known problems between powerline and VDSL?

Does this speed dropping sound familiar to anyone with homeplugs?

Is it possible to prevent the homeplug frequencies from interfering with VDSL?

[jelv]

Router & modem downstairs in master socket, homeplug 600Mbps plugged in to same 6-gang extension lead as HG612 modem and ZyXEL VMG1312-B10D, homeplug 600Mbps upstairs in office (on different ring main) to 1gbps switch, PC plugged in to switch. Also two 200Mbps homeplugs linked to 600MBps homeplugs.

Recent speed test result from PC:

[cbdeakin]

And you should be getting close to 80mbps, correct? The latency seems a little high too, but maybe thats unrelated.

Does the switch have any effect at all?

[jelv]

The homeplugs do affect the latency (directly wired to the router it's well below 20), but that's the only issue I actually see.

I've used a switch for years and never seen any effect - I did upgrade from 100Mbps to 1Gbps when I got VDSL.

[meritez]

And you should be getting close to 80mbps, correct? The latency seems a little high too, but maybe thats unrelated.

Does the switch have any effect at all?

what type of vdsl filter do you have, dangly microfilter or master socket nte5 mk type?

[underzone]

Yes. Get rid of them.
Prepare to install Cat6 cable instead...

[sevenlayermuddle]

I noticed that when downloading files, my speed drops down to about nearly half, from ~50mbps down to ~27mbps. This generally only happens every 1-2 minutes  (usually) for a few seconds, but sometimes the speed drops multiple times.

So just to be clear, is it the case that your data throughput drops temporarily, rather than a reduction your dsl sync rate?

One possibility then would be that it is a problem with the source from which you are downloading, unable to provide the data as fast as your broadband connection is allowing you to consume it.   

[fat jez]

I have experienced dropped VDSL connections while using home plugs.  ADSL was unaffected, same Huawei modem used for both, same router.

[cbdeakin]

I'm considering just using EE 4G with a router instead.

Presumably, a 4G router would be unaffected by homeplugs / powerline?

I might even be able to get higher speeds than VDSL where I live, since the sync rates are limited by the shittyness of ECI VDSL cabinets, lack of G.INP and distance from the cab.

I doubt I would be able to persuade my family to stop using homeplugs, even though they get disconnections every day or so (I've been using Wi-FI instead).

My dad might be willing to install ethernet cabling by drilling some holes around the home, but this will have to wait a few months.

It would be ideal if I could confirm this problem is caused by powerline interference. Does anyone know of a way of to monitor the VDSL signal in realtime and check for interference?

Or, is there a reliable way to filter out any powerline noise from the VDSL signal?

Note - The VDSL connection does not drop. The download speed falls every couple of minutes by a varying amount, I've been tested it by downloading 1gb files from here:
https://www.thinkbroadband.com/download

It has been happening more consistently today and it still happens when I use bandwidth control to limit bandwidth to other PCs in the LAN. Also, if I limit download bandwidth on my own PC to 10 / 20mbps, the same drop in throughput occurs.

[cbdeakin]

There's a guy here (link - https://community.virginmedia.com/t5/Networking-and-WiFi/TP-Link-PA9020P-ethernet-powerline-kit-speed-REDUCED-when-I/td-p/3768109/page/7)
 who had his Virgin Media internet speed cut from 350mbps to 170mbps when using homeplugs. He somehow fixed it by using an Archer C9 router in between his homeplug and Virgin modem.

The chipset the Archer C9 uses is: Broadcom BCM4709. I wonder if there is something different about this chipset that prevents or blocks interference?

This seems odd to me as a 350mbps connection would use DOCSIS / hybrid fibre rather than VDSL (please correct me if I'm wrong). Maybe powerline adapters overlap with these frequencies also?

[Alex Atkin UK]

I'm considering just using EE 4G with a router instead.

Presumably, a 4G router would be unaffected by homeplugs / powerline?

If you think the speed dropping from the homeplugs is bad, don't even think about going 4G.

VDSL is infinitely more reliable than 4G unless you are very very fortunate in your area.  Latency is never going to be as good either, even with a perfect 4G signal.

[cbdeakin]

Could the drop in download speed be related to varying SNR margin (caused by powerline interferance)? I noticed that it often drops from 6.1 to 6.0 during downloads. It drops at other times to but I need to monitor more to see by how much.

If the problem is related to SNR or SNR margin, I wonder if setting the SNR margin higher could help? I think there are modems that allow this.

[sevenlayermuddle]

You may just be observing perfectly normal flow control that kicks in transiently during transfer of large amounts of data.

Is the elapsed time for the downloads of these large files broadly consistent with your DSL connection speed?   Or alternatively, does the TBB speed test roughly match up to expectations?

[cbdeakin]

I noticed that the Downstream and Upstream Max Rate often changes a small amount every few seconds too.

The SNR margin also varies when the line is idle. Also, the SNR remains at 6.1 (downloading via WI-FI or not) on the modem at night when the homeplugs are presumably idle.

[j0hn]

The SNRM fluctuates up and down all day long.
It can go up/down 0.1dB multiple times a minute.
Such small variations are of no concern.
Same goes for the max attainable rate.

My homeplugs didn't affect my SNRM at all but they sent my FEC rate through the roof.

I always advise against their use.