Upload speed randomly drops from around 20 Mbps to 5 Mbps

[#1]

I've been trying to think what could be going on but the only things I can think of are that we do live by a big school and various factories, offices and retail parks, plus the installation of an FTTP network in the area seems to have been going on for ages. However, I can't think of anything specific taking places on Wednesdays and this has been going on for months.

The pattern does at least suggest that the problem is not my own wiring.

Andy

[#2]

It's a very odd issue indeed @AJK. Realistically, there isn't a whole lot we can do at this time to implement a resolution as; it's happening quite infrequently, has a (relatively) low impact on the service, and we have no idea what's causing it. If I had to hazard a guess (and this really is just a guess, nothing more) it sounds like electrical interference might be at play. There have been strange incidences in the past where neighbour's electrical appliances can impact the network, an example of this that always sticks out in my mind being the time it was discovered that an old CRT TV being turned on at the same time every morning was causing an entire village's ne...

Now, that was a very unique case and most likely not what's happening here, but it might be worth asking your neighbour's if they've been having any issues on Wednesdays too. 

[#3]

Is there any possibility that the measured slow speed is due to other activity on the network - such as background cloud storage (Dropbox / One Drive / iCloud) synchronisation activity or (if these tests were done soon after switching on the PC) due to Windows update activity?

Remember that with Win10 upwards, left to itself, Win10 can run as an update DISTRIBUTOR.

[#4]

Hi @Townman 

Thanks for your reply.

No, I don't think that would apply as the initial speed tests are done internally overnight by the router and then confirmed by me with further tests.

I mentioned how the previous three Wednesdays were affected days so I thought that was a pattern but this week it started on a Tuesday. So, yesterday, Wednesday, after rebooting the router and getting things back to normal I decided to bite the bullet, disconnected my own router, mesh network and modem and plug in my old Hub 1. All was fine yesterday, with downloads and uploads consistently around 72 and 20 respectively. Today downloads have plummeted to consistently less than half normal and uploads down just a tad. These tests are with BT wholesale and ookla.

I don't want to keep rebooting the PN Hub 1 just yet so I'll leave it a bit to see what happens.

Typical, just after originally posting this reply my next test produced normal speeds again, 72 up and 18 down, so I think something else was going on this morning and things are back to normal this afternoon.

Unfortunately I'm going to have to leave the Hub 1 one for some days for it to be a meaningful test. 

[#5]

I think that this is a good tactical approach.  The Hub One is a BTHH5a ... for which there is a load and go version of Router Stats (see the link below).

Can you please give consideration to downloading, installing and running that 24x7 please?  I recommend setting the sample interval to 10 seconds, with 720 points per graph.  Only really interested in the SNRM plot.

If it is clean, then I think that Plusnet needs to look at the VLAN back haul loadings from your exchange ... on the other hand, if the SNRM is messy, then you have a REIN issue ... which is a different bag of worms.

Right now, there is nothing specific which points to the cause of your experience, so some investigation can only prove helpful.

[#6]

Thanks for the helpful info @Townman 

I shall see what I can do.

My plan has been to see if the Hub One appears to give consistently acceptable and speeds and no sudden dropping and sticking of uploads to about 5 Mbps. If that happens then I suspect there's something odd with my Draytek and Google Nest combo or the Draytek is more sensitive to something on the line. If Hub One passes the test then I'd try the Hub 2 which would allow me to try it as just a modem with my Google Nest handling the router and Wifi side.

Having said all that if I can just get some router stats to help rule things out of find a fault that would be good. Is it worth me trying the Draytek again and getting stats from that or just stick with the Hub One?

[#7]

If this were my problem, I would stick with the Hub One and the BTHH5a router stats combination.  I know for sure that they work well together and working with the Hub One eliminates any possibility of Plusnet using the "not our router" card.

What I seek to identify or rule out is local intermittent interference ... which could give rise to the scenario you have described ... intermittent slow performance.  Bad SNRM plots look like this...

This graph shows variability on both the DS & US - things look fine until 18:30 - then something causes a disconnection after which the (much slower) connection is besieged with REIN.  From 18:30 one would expect rather poor throughput speeds.

[#8]

Okay @Townman @TheMightyAJ I'm finally able to get back on this.

I was able to leave the router stats running for a few days to cover the days most likely to experience the problem. Everything seems normal in the charts. Just one day had some blips as seen in the attachment but I assume not enough to cause a problem. I didn't experience any speed issues while running on the Hub 1 for over a week, but after a week or so on my own kit the upload speed this morning was stuck at 5.6 Mbps again. A reboot fixed it again.

I think I'm going to have to get a Hub two, see how that works, then try that just as a modem with my google nest wifi handling the wifi. Hopefully I am right in thinking that's still possible?

Thanks for your help.

Andy

[#9]

I would be a little concerned by that plot. That’s a fairly nasty spike. -4dB if the service were running at 3dB you would be seeing disconnects and then slowing speeds. Personally I’d keep monitoring for a while with the hub one.

I’ll take another look at that graph when I’m next in the PC - it’s not clean enough for my liking!

[#10]

As promised, I have reviewed this on a proper screen.  The SNRM plot is not smooth.  The mean line is neither 3dB nor 6dB suggesting a change in background noise since the last sync.

• More noise if the target SNRM is 6dB
• Less noise if the target SNRM is 3dB

I think that there is something here needing further inspection.  Can you please do a resync during daylight hours and continue running routerstats 24x7.  Post the resync, the SNRM should be 3dB or 6dB - keep a watch to see how / when it changes.  Try to correlate those changes with switching of electrical equipment.

A good plot should look nice and flat like this (after the two ugly transients!!) but at 6dB.

Can you correlate the spike on your graph with the use of the telephone?  Note that many claim that the do not use their telephone - they do not have one plugged into the line - which simply means that they have no idea if there is an incoming call on the line.

[#11]

Thanks for your time and help @Townman 

So what you're saying is the line looks generally a bit noisy and it's not just those spikes?

By resync I assume you mean disconnect the modem and leave a few minutes before reconnecting?

When I started running the router stats it wasn't long after connecting the Hub One and that would have been a resync. I've attached what was the first page of stats.

I'm pretty sure that one spike was when someone was on the phone because I was watching the stats when that call started. I couldn't replicate it and subsequent calls didn't produce anything in the stats.

The most recent time the speed reduction started I had checked the speed, last thing at night and first thing in the morning so no devices switching on, or any changes in the house to interfere with it.

I will try it again soon, like you say, and see what I get.

Thanks again.

[#12]

Yes to all of the above.

4dB and 10.5dB are simply not the right figures.

It would be good to see the SNRM plot through a re-sync process.  Just pull the xDSL wire, wait a minute or so and plus it back in.  Make sure that router stats is running throughout.  Note the xDSL up entry in the router systems log.  That will contain speed and target SNRM values.

[#13]

I started recording more stats this morning but forgot to leave routerstats running during the resync process so have now done that. I've attached the first two images which started recording within minutes of connecting the old Hub one this morning. I'll get the resync capture later.

[#14]

Can you also grab the router log records for the xDSL establishment please.

The US SNRM looks to be targeted at 9dB - what is the US sync value?

The DS SNRM is neither 3dB nor 6dB - if the target is 3dB and the line is running near 24mbps then 4.5dB (sub 6dB) is not quite the concern I was considering. 

[#15]

Sorry, where do I find records for the xDSL establishment and where do I confirm the US sync value?

Thanks.