Speed reducing to set amount at regular interval when downloading files.

[#1]

Hi,

I’m trying to understand/fix a problem I’m having with my new full fibre 900/112 install.

On the surface things seem fine at first but now I’ve had a chance to use it I’m finding an odd problem keeps occurring.

In a nut shell the problem is that when I download a large file say from here, http://speedtest.tele2.net/, it will start to download it at a speed I would expect but then after a short while the connection speed suddenly drops off a cliff and goes from say an average of 700mbps to 300mbps. It then stays like that for a short while and then suddenly jumps back up to 700mps, then a short while later it drops off a cliff again and goes back to 300mbps.

Now i appreciate that internet speeds can fluctuate but I find it hard to believe it’s a problem with the internet as a whole because it always drops to the exact same speed and the interval of how long it drops for seems to be the same every time.

It is not limited to just http://speedtest.tele2.net/ either. Downloads of different Linux distribution ISO’s from multiple mirror sites produces the same results and it is always the exact same speed it drops too.

What baffles me even more is that randomly it will download a file at 700mps without any problems and continue to download the whole file at that speed. Sometimes I can even download the same file again a few moments later and it will continue to download at a relatively solid 700mps. But then a can do it again a few moments later and its back to dropping off a cliff at a fixed speed and timing. If I were to download a file 10 times I’d say 2-3 of those times it would download at 700mps without issue but the other 7-8 times it does the regular interval cliff drop.

I’ve included an attachment of the effect I’m trying to describe and if you look at the fluctuation when it’s around the 700mps that is what I would expect from the internet being the internet. The constant intermittent drop however looks too clean and measured like something is artificially reducing the speed to a set amount each time.

This is not limited to just a single computer or windows as it also happens on a Freebsd and Linux based OS I’m using as well.

They are all using a wired connection.

Nothing else is using the line at the same time I’m trying to download. It’s just a single computer connected to the hub.

I’m using the Plusnet hub 2.

Any help appreciated.

[#2]

Nothing else is using the line at the same time I’m trying to download. It’s just a single computer connected to the hub.

@chaoticmess is there anything trying to upload e.g to a cloud drive at the same time ?

Downloading will still require some upload bandwidth for acknowledging the download data,  although with a 115Mb upstream you wouldnt expect that to be a problem.

TBH your 700Mb speedtest looks a bit 'off' , you would expect much closer to 900. I have a 900/115 connection and speedtest usually shows 910 down and 110 up. Try the cli version https://www.speedtest.net/apps/cli as that gives much more consistent results 

[#3]

Thanks for the reply.

I have already run several speed tests and like I said above, at first everything seems fine and I get the speed I would expect.

The problem is with real world usage when downloading files this problem occurs. It also seems to require time for the problem to kick in and the speed tests don’t last long enough for that to happen which is why they make it look like everything is fine.

Here is the link to the cli speed test result: https://www.speedtest.net/result/c/fa2abdd4-57d1-4058-bfec-5ea594d67283

Nothing is uploading at the same time I’m downloading. I don’t use cloud services and have windows updates policy controlled so I can do them when I want. It’s a bare bones fresh install with nothing running on it to cause a problem.

[#4]

Ah! I hadnt appreciated from your first post that it was just file downloading that was the problem, I thought speedtests were not right also.

If its just downloads,  can your storage handle the sustained write speeds ? Or it it just the,servers you're downloading from that can't keep up ?

[#5]

I was going to ask a similar question, @MisterW . Surely, both the originating servers load/speed and the OPs write speed/buffer are the limiting factors here?

[#6]

I don’t think it’s either of those things as it happens to both Crucial and  Samsung nvme drives and if it was just one or two servers giving me problems I could accept it was those servers causing the issue but it can happen with any large file I download from anywhere so long as the file is big enough to allow say 15-20 seconds to pass.

I also have access to a dedicated server hosted on the internet that has 1gbps download and upload and it can download the same files at its full line speed so I know the servers are capable of providing the speed.

[#7]

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@chaoticmess wrote:

I also have access to a dedicated server hosted on the internet that has 1gbps download and upload and it can download the same files at its full line speed so I know the servers are capable of providing the speed.

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On the same equipment at your end?

[#8]

No the dedicated server is running esxi with some VM’s and a opnsense VM being the router. The dedicated server isn’t anything to do with the problem. I was just mentioning it because it proves the servers I’m downloading from on my home plusnet line are fully capable of delivering 1gbps so its not the servers I’m downloading from that drop the speed.

I can also transfer large files over my local home LAN at a constant @960mbps so the drives are fully capable of accepting near 1gbps speeds.

I was hoping to keep things relatively simple but to further add other things I’ve tied and have been successful but I don’t understand why…

I’ve tried using a spare computer with opnsense on it as a replacement router for the hub 2. On its own it suffers from the same problem as when I use the hub 2.

However I also have another computer with opnsense running on it exclusively running as a vpn client through the plusnet line via the first opnsense computer acting as the main PPOE router.

What I don’t understand is when I download a large file using both the PPOE opnsense router to replace the hub 2 and connect through the vpn connection on the second opnsense computer I can sustain around 650mbps download speeds without the speed dropping at regular intervals.

As soon as I try and replace the PPOE opnsense computer with the hub 2 I get the same reduction in speed even though I’m still connecting through the vpn computer only now its via the hub 2 that’s making the PPOE connection.

It makes me feel like it’s a problem with the hub 2 and some sort of setting or hardware limitation or something like that.

Having tried researching the problem I was wondering more if it was a problem with how PPPOE works, MTU settings and similar settings like that as I can get something approaching working when I remove the hub 2 and connect through the vpn yet if I use the hub 2 on its own or with the vpn it gives the same problem.

I hope that makes sense.

[#9]

@chaoticmess A little bit over my pay grade, but maybe it makes more sense to @MisterW if he comes back.

[#10]

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@chaoticmess wrote:

I also have access to a dedicated server hosted on the internet that has 1gbps download and upload and it can download the same files at its full line speed so I know the servers are capable of providing the speed.

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Are you certain the 1gbps download speed applies to all the connectors and cabling inbetween the devices ?

[#11]

@chaoticmess 

I’ve tried using a spare computer with opnsense on it as a replacement router for the hub 2. On its own it suffers from the same problem as when I use the hub 2.

It makes me feel like it’s a problem with the hub 2 and some sort of setting or hardware limitation or something like that.

wouldn't the 1st statement above contradict the 2nd ?

AFAIK the Hub2 is perfectly capable of sustaining 900Mb download

[#12]

I get what you’re saying but what I mean by what I said was that I believe it’s a setting that needs to be configured properly on both and they don’t contradict each other, they simply agree with each other and give the same problem even though they are different hardware and software.

Difference that makes me think the hub 2 is more of a problem than the opnsense router is that the problem still persists if I connect through the vpn computer via the hub2 where as the problem goes away if I connect through the vpn via the opnsesne router. That makes the hub 2 more problematic in my view.

Just to clarify: When I use the hub 2 no matter what else I do the problem persists. However when I don’t use the hub 2 I can get something to work but only through a vpn connection.

This doesn’t make sense to me as in my mind, if anything, it should be the other way around. The hub 2 should download fine and at full speed and the vpn connection should suffer mtu or some other miss-configured setting yet somehow using the opnsense vpn computer and a opnsense computer to replace the hub 2 stops the speed reduction at regular intervals.

[#13]

Is your opnsense router configured with the same lan ip,subnet and dns servers as the Hub 2 ?

[#14]

Yes, it’s the same.  They both use:

IP: 192.168.0.254

Subnet: 255.255.255.0

DNS:

212.159.13.51

212.159.13.52

They’re not active at the same time though. I disconnect the hub 2 then connect the opnsense router and vice versa when switching between them.

[#15]

Might be worth a read through this https://forums.thinkbroadband.com/fibre/4727755-download-speeds-on-bt-fttp-slow-when-not-using-a-vpn...