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Author Topic: Do Homeplug AVs wreck VDSL2 signals?  (Read 11151 times)

cbdeakin

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #15 on: December 14, 2019, 01:43:38 PM »

I see a lot of Upstream packet errors (> 4 billion) after the router is reset. Sometimes it happens throughout the day too. If I reset the intergrated modem only, the error counter usually shows 0 upstream and downstream errors.

I wonder if this is related to homeplugs interfering with the VDSL frequencies?

Is there really no way to weaken or block the interference? What about connecting each homeplug to an extension lead or surge protector with a low pass filter?
« Last Edit: December 14, 2019, 01:51:47 PM by cbdeakin »
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sevenlayermuddle

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #16 on: December 14, 2019, 02:18:51 PM »

If we convert that error counter to hex, 4294967294 becomes FFFFFFFE.

That’s far too interesting a bit pattern to be a count of the actual number of errors.  I’d therefor suggest it might just be a quirk of the software that is displaying it, and that it certainly does not mean there’s been 4 billion upstream errors. :)
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niemand

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #17 on: December 15, 2019, 01:14:43 PM »

Homeplugs triggered banding on an old VDSL line of mine.

Anything other than the most basic ones are big noise generators for VDSL.

Check the options on it. Might have a mode specifically avoiding the VDSL frequencies - the ones I was using did. Came at the expense of a bunch of performance, though.
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cbdeakin

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #18 on: December 15, 2019, 04:40:55 PM »

Thanks. I will check the frequencies on the older homeplugs, they seemed to work well enough for Internet use in my house if I recall correctly. Do you mean HomePlug AV 200mbps? Or do you mean older models than that (non AV homeplugs)?

I tried the PLC - VDSL frequency interference  avoidance mode but it didn't resolve the issue. AFAIK, all this does it set the homeplug to work in SISO mode.

 I also tried connecting the AV 1200 mbps homeplug next to my router to a surge protector with an RFI filter inbuilt. EDIT - I'm still getting brief throughput drops of upto 60% on the downstream, which is consistant with performance drops studied in academic technical reports.

I wish there was a way to restrict / choose what frequencies they operate on.
« Last Edit: December 15, 2019, 04:54:12 PM by cbdeakin »
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niemand

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #19 on: December 15, 2019, 05:03:34 PM »

The VDSL frequency avoidance is broken, then.

The whole point of the functionality is, as it says, for them to not transmit on VDSL frequencies.

Is it possible perhaps to get the homeplugs a few metres away from the VDSL modem and cables by putting them in a distant socket and connecting via an Ethernet cable?

Should help.

https://forum.kitz.co.uk/index.php/topic,18651.0.html
« Last Edit: December 15, 2019, 05:13:41 PM by CarlT »
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sevenlayermuddle

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #20 on: December 15, 2019, 05:57:00 PM »

I also tried connecting the AV 1200 mbps homeplug next to my router to a surge protector with an RFI filter inbuilt.

What about connecting each homeplug to an extension lead or surge protector with a low pass filter?

If you mean you connected the homeplugs to the mains through a mains extension with surge protection or low pass filter then that could be the cause of  any problems you are experiencing as it will most likely cause errors in the comms between home plugs.  Home plugs need clear and uninhibited connection to the mains in order to work.

Tbh, whilst home plugs do sometimes/often cause problems, nothing you have said in this thread convinces me that they are causing a problem on this occasion.   

I’m still not clear what is actually worrying you.   An occasional blip in network activity, during data transfer, does not in itself prove there is a problem with the DSL connection, providing overall data throughput is as expected.     Your connection appears stable, your SNR margin sounds stable, and the only error counter you have posted is clearly not an actual error counter (see reply #16).

I don’t think you’ve yet posted the results of an actual speed test, such as TBB?





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tiffy

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #21 on: December 15, 2019, 08:31:40 PM »

From my limited dealing with HomePlugs of various makes have always found that they won't work through any form of surge protector/filter adaptor, always had to connect directly to the ring main.
May have been just my particular combination of HomePlug's/Filter-Surge Protector's ?

Early days, I have used HomePlugs when on ADSL-2 service and after migration to VDSL-2, perhaps I've been lucky but never had any issues with noise as monitored by RouterStats & DSLStats.

Currently don't use any HomePlugs as I've had the time to run quite an extensive, hard wired LAN system, not too difficult in a timber framed bungalow, obviously this is the way to go if at all possible and will always be superior to HomePlugs or Wi-Fi.   
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cbdeakin

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #22 on: December 16, 2019, 01:38:30 AM »

The VDSL frequency avoidance is broken, then.

The whole point of the functionality is, as it says, for them to not transmit on VDSL frequencies.

Is it possible perhaps to get the homeplugs a few metres away from the VDSL modem and cables by putting them in a distant socket and connecting via an Ethernet cable?

Should help.

https://forum.kitz.co.uk/index.php/topic,18651.0.html

Good advice, thanks. I recently asked my dad if I could move the homeplug to another socket but he's quite concerned about the aesthetics of the hall, where the master socket is located. I could try this on a temporary basis to see if it fixes the problem, as it's very easy to test.
« Last Edit: December 16, 2019, 02:01:58 AM by cbdeakin »
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cbdeakin

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #23 on: December 16, 2019, 01:44:59 AM »

If you mean you connected the homeplugs to the mains through a mains extension with surge protection or low pass filter then that could be the cause of  any problems you are experiencing as it will most likely cause errors in the comms between home plugs.  Home plugs need clear and uninhibited connection to the mains in order to work.

I only added a surge protector recently as a test. Before, the homeplug was plugged directly into a power socket. It doesn't seem to have effected the performance, as far as I can tell it has made no difference.

Basically, I need to connection to remain stable at around 40mbps or higher. Newer streaming services like Google Stadia can use upto this amount and suffer if there are drops in bandwidth.

Here's an example of the issue while downloading a game via the Epic Game Launcher (the throughput is dropping approx. the same amount as test file downloads on thinkbroadband.com) :
« Last Edit: December 16, 2019, 02:24:30 AM by cbdeakin »
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sevenlayermuddle

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #24 on: December 16, 2019, 09:28:24 AM »

Problems caused by home plugs would be reflected in DSL error counters and probably dips in SNRM or, if extreme, in DSL connection drops.

In my experience a blip in a throughput graph is not necessarily indicative of a problem, providing that overall throughput remains adequate. 

Blips may of course imply errors and retransmissions but they can also be caused by normal flow control procedures applied by the protocols, or if some other activity is competing with the file download for network bandwidth, or if some other activity is competing for disk or CPU access within the destination PC.   If you’re using WiFi for the test then that’s another thing that might cause throughput blips.

Remember too that, depending on sampling rate, the graph may make the blips look worse than they are.   Streaming services usually employ buffering that will survive blips, as long as they are short.

I’m not defending home plugs, they have a terrible reputation and I’m sure it’s justified.  But in your case, if eliminating the home plugs is a big upheaval then I’m not yet convinced that doing so would eliminate these blips. 

You did say earlier that you were getting disconnections every day or so.   Is it worth expanding on that, as it might be more indicative of a DSL problem?

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jelv

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #25 on: December 16, 2019, 10:33:40 AM »

Tbh, whilst home plugs do sometimes/often cause problems, nothing you have said in this thread convinces me that they are causing a problem on this occasion.   

+1
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jelv

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #26 on: December 16, 2019, 10:40:42 AM »

IF the homeplugs were messing up the VDSL I think you'd be seeing far more issues than the occasional blip in download throughput.
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niemand

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #27 on: December 16, 2019, 11:28:08 AM »

The homeplugs don't transmit at the same power all the time. They go into lower power mode when traffic is minimal and increase power and, hence, bitrate, throughput and interference level, when they need to.

Bursts of errors when connection is under load, manifesting as throughput drops, would be an indicator of these issues.
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sevenlayermuddle

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #28 on: December 16, 2019, 12:00:06 PM »

The homeplugs don't transmit at the same power all the time. They go into lower power mode when traffic is minimal and increase power and, hence, bitrate, throughput and interference level, when they need to.

Bursts of errors when connection is under load, manifesting as throughput drops, would be an indicator of these issues.

Yes but when maintaining a large file download of constant data rate for duration of a few minutes or more, if interference were occurring, I’d expect to see a corresponding dip in SNRM, for roughly the duration of the download.   

It’s a while since I looked at DSL protocols but isn’t the SNRM that is shown by the router calculated by an algorithm comparing current BER with some reference BER (that reference being regarded as zero margin)?   If so, it’s hard to see how BER could increase without SNRM dropping.
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jelv

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Re: Do Homeplug AVs wreck VDSL2 signals?
« Reply #29 on: December 16, 2019, 12:18:09 PM »

I've just tried downloading the 1GB test file from TBB and monitoring the stats while it was in progress. The download was running at over 8MBps (around 65Mbps), during the down load there were a couple of brief drops of SNRM from 6.6 to 6.5, but I see similar drops when not downloading. My homeplug is within 2ft of the HG612 modem.
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