Everyone stumped by slow upload speed problem (Zen 80/20)

Hi,

We've been with Zen for 2-3 years on an FTTC 80/20 connection and have had little to no problems during this time.

About 3 weeks ago however we started having a problem with infuriatingly slow upload speeds (0.5-2mbps) on several testers, but it was almost unusable in reality.

Before this issue, we would consistently get 75/18~ Mbps and now we are getting 75/1~ Mbps. So the download speed is still completely fine but the upload is now extremely poor. I should note that when trying to run a speed test, the upload test takes 15-20 seconds before it even starts?No idea why.

We have tried changing everything our side of the test socket :
Factory resetting the modem router twice, updating the firmware, changing the filter, changing DSL Cable but to no avail.

Zen have suggested that one of our devices could be hogging the upload but they admit the line saturation is very low and we've tried connecting one computer at a time over ethernet and disabling WiFI. (Didn't make a difference when trying with several different machines, all fairly new.)

We thought it might be an issue with the supplied modem router (Fritzbox 3490) so we went out and bought a test modem/router and used that over ethernet but we have the exact same problem. So at this point, we are extremely confident it's not an issue our side of the test socket as we've isolated everything and switched it out for something else.

Our sync speeds are still completely fine (80000/20000) and Zen say there are no problems with the line tests they have run. They tried switching us to a different area on their backend (whatever that means) but it didn't help. At this point Zen says there is nothing else they can think of so they agree to send out an Openreach engineer to see if it's a problem with the line.


Guess what: The Openreach engineer arrived this morning and said there is absolutely nothing wrong with our line but is also satisfied it's not an issue our side of the test socket. He doesn't have a clue what's going on. He said he'll speak with our ISP..and am now waiting for more correspondence.


What is going on???

In summary:

- Everything our side of test socket has been switched out/isolated.
- Zen says there are no line faults and sync speeds remain at 80000/20000
- Zen have tried moving us to a "different area on their backend"
- Engineer sent out by BT says there is nothing wrong with our line but also believes it's not an issue on our end.

Thanks for any input.

Edited by AstroflashTB (Thu 05-Sep-19 11:23:59)

Any chance of a link to a speed test down at https://www.thinkbroadband.com/speedtest
With the idle, download and upload latency testing you can tell if the slowness is due to a lot of download/activity i.e. the idle latency will be poor and similar to either of the download/upload figures.

Also did Zen support get you to run the speed test that lives on their network? i.e. removes variables from Internet

Most likely explanation is that there is a congestion or backhaul problem affecting you.

In reply to a post by MrSaffron:

Any chance of a link to a speed test down at https://www.thinkbroadband.com/speedtest
With the idle, download and upload latency testing you can tell if the slowness is due to a lot of download/activity i.e. the idle latency will be poor and similar to either of the download/upload figures.

Also did Zen support get you to run the speed test that lives on their network? i.e. removes variables from Internet

Most likely explanation is that there is a congestion or backhaul problem affecting you.

Most of the tests were performed on Zen's tester.

Here's the link to the TB one! https://www.thinkbroadband.com/speedtest/15676853007...


Thanks

Edited by AstroflashTB (Thu 05-Sep-19 13:11:12)

Idle latency was 27ms which is OK given its a small TCP packet in that test

When downloading this rises to 175ms, to be expected
When uploading the figures recorded were 25,26,26,25,255,25,27,29,26 to average of 51ms, but the low values close to idle otherwise suggest nothing was saturating the upload.

No 100% idea what is wrong...but a lift and shift to a different port in the VDSL2 cabinet if not already tried might be useful, i.e. while sync is good the poor upload may be down to something wrong with how that port is handled.

If the low upload was a cap/throttle issue on the ISP or Openreach side I've have expected a flatter line from the upload (most common is 1.8 Mbps upload, i.e. on a 40/2 product by mistake).

Zen might want to move you from their LLU/partner backhaul onto the standard BT Wholesale or the other way around (from original post this might already have been tried).

Have tried digging into your history and

https://www.thinkbroadband.com/speedtest/15661421668... 18th Aug has better upload using the PC
https://www.thinkbroadband.com/speedtest/15652093667... 7th Aug shows issue been present a while and from that test I'd have suggested you are on an impossible Openreach setting of 80/2 i.e. product that does not exist

Looking into what was different on the 18th might give some clues as to what problem is.

One wildcard looking at the tests I can see they all appear to be PC/laptop based and a chance you have the same Anti-virus/malware installed and a version is mucking around with your upload traffic limiting the speed. So while testing over Wi-Fi is often seen as bad, testing with a mobile/tablet is a good way of ruling out operating system/AV interactions.




I know you have tried to rule out your hardware and a good way to show that it is not that is to visit somewhere else with a phone and test over their wifi and compare to result on your wifi.

In reply to a post by MrSaffron:

Idle latency was 27ms which is OK given its a small TCP packet in that test

When downloading this rises to 175ms, to be expected
When uploading the figures recorded were 25,26,26,25,255,25,27,29,26 to average of 51ms, but the low values close to idle otherwise suggest nothing was saturating the upload.

No 100% idea what is wrong...but a lift and shift to a different port in the VDSL2 cabinet if not already tried might be useful, i.e. while sync is good the poor upload may be down to something wrong with how that port is handled.

If the low upload was a cap/throttle issue on the ISP or Openreach side I've have expected a flatter line from the upload (most common is 1.8 Mbps upload, i.e. on a 40/2 product by mistake).

Zen might want to move you from their LLU/partner backhaul onto the standard BT Wholesale or the other way around (from original post this might already have been tried).

Have tried digging into your history and

https://www.thinkbroadband.com/speedtest/15661421668... 18th Aug has better upload using the PC
https://www.thinkbroadband.com/speedtest/15652093667... 7th Aug shows issue been present a while and from that test I'd have suggested you are on an impossible Openreach setting of 80/2 i.e. product that does not exist

Looking into what was different on the 18th might give some clues as to what problem is.

One wildcard looking at the tests I can see they all appear to be PC/laptop based and a chance you have the same Anti-virus/malware installed and a version is mucking around with your upload traffic limiting the speed. So while testing over Wi-Fi is often seen as bad, testing with a mobile/tablet is a good way of ruling out operating system/AV interactions.




I know you have tried to rule out your hardware and a good way to show that it is not that is to visit somewhere else with a phone and test over their wifi and compare to result on your wifi.

Thanks for your help.

Regarding the AV, the ethernet was tested on my desktop PC and a desktop iMac. Neither has any AV installed other than the default. I've tested WiFi on a Macbok Pro, my Android phone, and an iPhone. All have the same issue and none have any third party AV software installed.

Regarding the 18th, that was the day I bought an alternative modem router (TP-LINK's TD-W9970) to try out to see if it made a difference. Although that test on this site looked alright (10mbps upload) it was not fine when tested several more times on Zen's site / fast.com (only getting 1-2mbps with that new router)
Just the day before yesterday, Zen made me factory reset the Fritzbox as they were still hesitant to send out an engineer and I was getting 10mbps on Zen's site/ fast.com but only 1mbps on thinkbroadband.com.

As I knew that was just a coincidence I ran the test again yesterday on Zen's own site and proved that I was only getting 1-2Mbps most of the time.

Hope that makes sense. Basically what I'm trying to highlight is that there is no consistency between tests/and different testers. I can on occasion hit 9-10mbps upload on random tests, but this seems to be rare.

Here's the result from my phone:

https://www.thinkbroadband.com/speedtest/15677025175...

Here's where it gets even weirder.

When trying to actually use the upload I get wildly different results depending on the service.

Uploading the 20MB (160Mb) test file from Thinkbroadband.com on:

Google Drive: Takes 1 minute so this is 2Mbps~
Mailbigfile.com: Takes 4 minutes so this is 700Kbps~
Gmail (file upload): After two minutes the file had barely done 5%. This is less than 100Kbps. This is the same across both desktops over ethernet.

Edited by AstroflashTB (Thu 05-Sep-19 18:14:48)

If seeing the 9-10 Mbps now and then suggests not a port config issue but something in the backhaul side.