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I just upgraded to the 900/110 package from BT as it was on offer for £1 extra over the 500 package
I notice in real world downloads I get nowhere near that, approx 300Mbps from Microsoft/Steam/Ea etc..
fast.com and the BT wholesale speed test always come back at 900+, so as far as BT are concerned all is good. The TBB speedtest varies a bit.
However if I enable a VPN on my PC and use that, all downloads are at near full speed, the tbbx1 test is vastly different.
Is this an issue within the BT network or just my local exchange.
Without VPN
With VPN
BT 900/110 Mbps
Edited by onthenet (Thu 22-Dec-22 11:41:38)
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For most users, getting poor speedtest results on high-bandwidth links is the result of problems at the client side. For example, your Windows anti-virus may be scanning stuff down the normal link, but not when the traffic comes down VPN.
I recommend you boot your machine from an Ubuntu Live CD USB stick, and do some speedtests using that. That will remove all Windows-related stuff from the equation, and give you a clean result.
If this demonstrates that everything works at full speed, then you will have been able to rule out any problem with BT's network, and know where to focus your attention on (i.e. your Windows configuration).
However if the Ubuntu test does show the same, then this rules out problems with Windows and you can more closely start investigating the upstream provider and their peering.
It does however seem very unlikely to me that BT would have a general congestion problem with traffic to TTB, Microsoft, Steam etc, and yet still be able to reach your VPN tunnel endpoint at full speed.
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Thanks for the advice, I did as you said and the result without VPN is below, much better looking.
I notice the tbbx1 test is still slower.
I tried downloading the Windows 11 ISO from Microsoft and it is hitting 100MBps+ 
Just running Windows Defender on Win 11, which is a relatively new install, time to go to Ubuntu !!
BT 900/110 Mbps
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If the only place you're noticing lower throughput numbers than you are paying for is the TBB speed test then I would just ignore the speed test.
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I tried downloading the Windows 11 ISO from Microsoft and it is hitting 100MBps+
Cool. That will be single threaded (assuming you're just doing an HTTP or FTP download, not Bittorrent or similar), so shows your link is good.
Microsoft might have a CDN node within your ISP's network, or close to it.
The Internet is a collection of independently-run networks, interconnected in a bunch of different ways. If you're only getting 400Mbps single-threaded download from TBB that could be due to a whole host of issues which are outside of the control of your ISP, and is not something to worry about by itself.
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No, as stated above, it was on Microsoft. Steam, EA etc, I was only using the TBB Speedtest to highlight the issue.
However all those issues have gone with the Ubuntu install.
BT 900/110 Mbps
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Awesome. Of course, if Ubuntu meets your needs then great (I'm a Mac and Ubuntu person myself).
Equally, now you know where the problem lies, it should be possible to tune Windows to work better. You'll need someone who knows the ins and outs of Windows to help you with that though.
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You'll need someone who knows the ins and outs of Windows to help you with that though. First step is to never install 3rd party 'security' software.
23 years of broadband connectivity since 1999 trial - Live BQM
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Yea, I learnt that many years ago, had been just running with Windows Defender.
I have now dual booted my machine with Ubuntu and it is so much more responsive, what is going on with Windows, can it not cope with a fast internet connection.
I tried my Wife's machine ,also Windows 11 and it is showing the same symptoms as mine.
I have to laugh though, six months ago the fastest I could get was 1.5Mbps, I was using Three 4G instead, which wasn't bad.
I then had to dig a 300M underground duct to my house from the road, all ducting supplied free by Openreach and now the TBB Speedtest says I am faster than 99.8% of tests in the UK
BT 900/110 Mbps
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Yea, I learnt that many years ago, had been just running with Windows Defender. Nice!
I have now dual booted my machine with Ubuntu and it is so much more responsive, what is going on with Windows, can it not cope with a fast internet connection. I tried my Wife's machine ,also Windows 11 and it is showing the same symptoms as mine. Very odd.. Ubuntu is good (I’m more a RHEL / CentOS on the server type guy) but it shouldn’t be that dramatic. I’m guessing faulty Network Interface Card driver somewhere. I lead teams that support a lot of hardware and Windows (10/11 etc on desktop) isn’t incapable of 940Mbps saturating a normal GigE port.
I have to laugh though, six months ago the fastest I could get was 1.5Mbps, I was using Three 4G instead, which wasn't bad.
I then had to dig a 300M underground duct to my house from the road, all ducting supplied free by Openreach and now the TBB Speedtest says I am faster than 99.8% of tests in the UK
Awesome result!
23 years of broadband connectivity since 1999 trial - Live BQM
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I’m guessing faulty Network Interface Card driver somewhere. I lead teams that support a lot of hardware and Windows (10/11 etc on desktop) isn’t incapable of 940Mbps saturating a normal GigE port.
I wondered that too, although it doesn't really explain why it worked at full speed over the VPN.
I guess it could be something to do with the VPN using a lower MTU. It shouldn't be IP fragmentation - Windows has been able to PMTU discovery for yonks - but as an experiment you could try setting the MTU on your PC's ethernet interface to 1492 (to allow for PPPoE overhead at the router).
Or it might be that using the VPN is bypassing things like TCP segmentation offloading on the NIC. This is supposed to make things work *faster*, but if it were a really crummy implementation, I suppose it could make things worse.
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I wondered that too, although it doesn't really explain why it worked at full speed over the VPN. Yeah, good questions, we'll never know
23 years of broadband connectivity since 1999 trial - Live BQM
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So in Windows I have disabled all services, except the Microsoft ones and all automatic startup programs and it looks a lot better,
Graph
Now to find out which one is causing the slow down.
BT 900/110 Mbps
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Awesome. You *should* get better single-threaded download than that, but it's probably an issue with your NIC driver. Buying a new NIC (preferably an Intel one, since they have very good drivers) ought to fix that. Intel chipset PCI cards can be picked up for about £10.
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I have the onboard NIC which is an Intel I219-V and also tried an old PCIe card I had lying about which is a Intel 82572 based card but I think it is about 15 years old !!
The onboard NIC driver is dated January 2022.
I get the same single threaded speed on both Windows and Ubuntu, it was only using the VPN that it went up to about 700Mbps, so that may be under my ISP's management.
Maybe they expect the 900 product to be used by a large family with multiple connections instead of just two people
BT 900/110 Mbps
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Nope.
Slow single-threaded performance means that a single TCP stream cannot be handled as quickly, in aggregate, as multiple concurrent TCP streams.
However, at the Internet (router) level, they are just IP packets. Your ISP does not distinguish between packets in different TCP streams (*)
This limits you to a few basic possibilities:
1. your router's NAT does not work well with a single stream (e.g. all packets for the same stream are processed by the same CPU)
2. your end PC cannot cope well with a single TCP stream (for similar reasons)
3. there is low-level packet loss, which affects the throughput of individual TCP streams via the formula here.
You can rule out case (3) by doing further tests to a speedtest server which is a medium distance away (say in mainland Europe) and a long way away (say USA). If the single-thread speed drops somewhat to Europe, and even more to the USA, then low-level packet loss could be the culprit. This is because the maximum speed is a function of both the round-trip-time and the packet loss level.
To rule out (1) and (2) you'd need to try with a different router and a different PC.
(*) Unless they are doing weird stuff like CGN - most "real" ISPs don't do that.
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It may be time to look at my router setup.
Currently running pfsense 22.05 on a Intel Core I5-4590
Now reading there are issues with a PPPoE connection and a fast connection while running pfsense.
BT 900/110 Mbps
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You could try PPPoE direct to your PC to rule that in or out.
It would be poor if an i5 can't do more than 365Mbps PPPoE on one core - that's only about 30K packets per second - but is certainly possible depending on how FreeBSD works.
I found this: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=20...
In comment 11 it suggests some sysctls:
* net.isr.maxthreads and net.isr.numthreads greater than 1
* net.isr.dispatch=deferred
You can ssh into your box, read these values with "sysctl", and try tweaking them if necessary (I'd be interested to see what the defaults are with pfSense).
However: I don't think this explains what you see, because it implies that *all* PPPoE packet processing would take place in a single interrupt handler - and therefore it wouldn't make any difference if the packets were from the same TCP stream or multiple TCP streams.
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If you want to test your local network speed to rule out windows drivers etc can I suggest using your own OpenSpeedTest server - there are versions for most OS: https://openspeedtest.com/selfhosted-speedtest.
Just beware you'll need to temporarily turn off the Windows firewall on the server.
That way you can test your drivers, NICs, switches etc without the WAN coming into play.
I also find it great for testing WiFi speed around the house etc.
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Checked out those variables and they are
net.isr.maxthreads = 4
net.isr.numthreads = 4
net.isr.dispatch = direct
During the speedtest the maximum WCPU was 9.5%
I will try the direct PPPoE connection later, going to have a couple of days to mess about with the connection.
changed the net.isr.dispatch to "deferred" but no difference, the others are read only and need to be changed in the /boot/loader.conf
BT 900/110 Mbps
Edited by onthenet (Fri 30-Dec-22 10:17:00)
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It may be time to look at my router setup.
Currently running pfsense 22.05 on a Intel Core I5-4590
Now reading there are issues with a PPPoE connection and a fast connection while running pfsense.
I use the Netgate 7100 at my office which uses a quad core Atom and get the below on an Openreach 1Gbps FTTP service.
The i5-4590 should have twice the performance per core of the C3558 in my device,
Thanks
Dan
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I can get those sort of results when connected via VPN but not when connected directly to ISP
There is probably not much in it between the C3558 and my 4th generation I5 but the network hardware in the 7100 would be much better, I think it supports up to 10G.
BT 900/110 Mbps
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I can get those sort of results when connected via VPN but not when connected directly to ISP
Since they are both going via the same router, the ISP, and both carried inside PPPoE, then this almost certainly points to a problem with your PC.
Did you try reducing the MTU on the NIC from 1500 to 1492? (It's a long shot but worth a try)
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Just an idea - can it be traffic shaping on the BT side? Or some kind of a packet inspection? Both options cannot affect the VPN speeds.
Can you do a speed test between you and your VPN entry point? If it's slower than VPN speeds that would mean that it's a difference between open and tunnelled traffic.
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I tried the MTU change but just the same.
I tried connecting directly to the ONT, and setting up a PPPoE connection on two different computers but the same result.
I can only get the the single thread download speed above approx 400 if using a VPN.
I tried the BT SH2 with only one PC connected, same result but works fine if VPN enabled
Thanks for all the advice and help, I'm just going to give up and use the VPN when downloading large files/Game updates etc...
The extra upload speed is worth the extra £1/mnth it cost me.
BT 900/110 Mbps
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If you want to test your local network speed to rule out windows drivers etc can I suggest using your own OpenSpeedTest server - there are versions for most OS: https://openspeedtest.com/selfhosted-speedtest.
Thanks for that, must have missed your post !!
Got that up and running and proves my internal network is working as expected.
BT 900/110 Mbps
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I did once get something similar to your issue, albeit on a much slower connection. On an FTTC connection syncing at ~65Mbps I was getting ~60Mbps throughput any time of day.
One day all of a sudden throughput was horrendous, often as low as a few Mbps, any time of the day, not just bad congestion at peak. Pop on a VPN and back up to 60Mbps speed tests any time of day including peak.
Pretty useless calling tech support - but a few other customers on their forum (and here) had similar. After a number of us kept records of the issue including someone with a SamKnows WhiteBox with a pecise graph of when the fault started raised high level complaints and got an article published on The Register the ISP finally listened and found some routing fault in their core network.
I guess the VPN was routed out onto the internet bypassing the issue in the ISPs core network.
I've not heard of that or would expect it on a BT connection though.
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Yes it is strange, but have been scanning through the forum and I see people with exactly the same issue with BT, but then it suddenly fixes itself as if there was a capacity issue or a routing issue.
The VPN works pretty much flat out all the time although it has it has side issues, eg when I tried to reply to this post I got this reply
You have been banned from making any new posts or sending private messages. The reason for this ban is: [ref: 49494907]Advertising fake COVID certificates is illegal.
I did try BT but they just do a speed test between the router and the exchange and it says 950.
I also downloaded a game yesterday from EA and without the VPN it came down at max speed for the entire download of 45GB, maybe a local CDN, Xbox downloads need the VPN.
BT 900/110 Mbps
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Yes it does have 10Gb interfaces but the ONT is only connected at 1Gb
Most benchmarks show the Atom having around half the performance of a 4th gen i5 so I'd definitely day you can rule out the router.
Thanks
Dan
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So after a messing around again, never one to give up, I ran TCP Optimizer from the following link.
TCP Optimizer
I selected speed as 100Mbps+, selected Optimal and applied.
Now everything is running perfectly, single threaded downloads are all full speed without the VPN.
The only thing that is slow is the TBBX1 test on TBB, even the download test files on here come down at full speed.
So will leave it at that for now, I have a backup of all settings changed if I need to revert for any reason.
BT 900/110 Mbps
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Do you know what the Optimiser optimised?
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These are the changes that were made when set to optimal from default.
TCP Optimzer changes
BT 900/110 Mbps
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Thanks. I’ll take a look.
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