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splovett
Aspiring Contributor
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Message 1 of 10

Understanding broadband speed issue

I recently upgraded from ADSL2+ to FTTC, at the suggestion of BT, only to find that my download speed was unchanged at 14Mbps but my upload speed halved from 1100 Kbps to 491 Kbps.  These rates remained pretty stable over a couple of weeks despite a couple of engineer visits to try and recover my upload speed - and the Openreach engineer successfulyy testing data upload on my line to a speed of 1.8Mbps.  Having been advised there is nothing more that can be done, I am due to be swapped back to copper this week.

What I would really like to understand, but nobody has been able to explain, is why switching to FTTC and the resulting shorter length of copper should reduce my upload speed so dramatically.  I've heard a lot about it only being 1/2 mbps less, but that is really significant when you are only starting with 1 Mbps.  I've also heard a lot about download being what everyone is interested in but that's hard to accept in today's world where most people sync / backup to the cloud and email photos to friends regularly - indeed my package came with 200GB of cloud storage - how long would it take me to upload even a tenth of this!

I understand that FTTC utilizes a much wider frequency band and that distance has a greater impact at higher frequencies. But, as I understand it the frequency range used for upload on FTTC is the same as for ADSL2+.  So why would the upstream rate be halved?

Please help me to understand the technical issue here.

Please also take the message back to the powers that be that upload speed is now important to most individuals - I accept that for most people it doesn't need to be as fast as download but 1/2 mbps really isn't fit for purpose any more - perhaps a ratio of 5:1 would be more realistic.

Many thanks to any and all that try to help me.

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Distinguished Sage
Distinguished Sage
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Message 2 of 10

Re: Understanding broadband speed issue

enter your phone number and post results remember delete number but leave exchange and cab 

http://www.dslchecker.bt.com/

Can you post stats from your hub

this gives some idea how speed drops off over distance

FTTC speed graph.gif



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lethal
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Message 3 of 10

Re: Understanding broadband speed issue

If the engineer was getting decent speeds and the line tests for him were good then it seems it could be an issue with the hub itself. When you are doing the speed tests, are you doing it with an cabled connection to the hub or over wifi? Have you tried testing the speed on other devices?

If over wifi, try doing a speed test on the device while connected to the hub and check if the speeds are higher than a wireless connection. Also the distance from the hub and any interference between it and your devices can also impact speed. Let us know how you get on and hopefully you can get the speed issue sorted. 

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Distinguished Sage
Distinguished Sage
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Message 4 of 10

Re: Understanding broadband speed issue

Your FTTC speeds are affected by your distance from the cabinet. The further you are from the cabinet the lower the speed. 

VDSL Fibre signal drops of quicker and is affected more than ADSL (normal) broadband by distance.

See graph.

FTTC-speed-distance-graph.png

If you use this checker and post a screen shot after you have removed your phone number. If you could also state how far you are from the cabinet it will let the forum members see what your line is estimated to get. 

http://www.dslchecker.bt.com/adsl/adslchecker.welcome


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Distinguished Sage
Distinguished Sage
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Message 5 of 10

Re: Understanding broadband speed issue

ADSL upstream frequencies are all together at the lower end of the spectrum and downstream at the higher end, VDSL upstream and downstream alternate in bands. Hence the frequency response is different for VDSL to ADSL.

Image result for adsl vs vdsl frequency

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splovett
Aspiring Contributor
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Message 6 of 10

Re: Understanding broadband speed issue

BT Broadband Checker.png

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splovett
Aspiring Contributor
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Message 7 of 10

Re: Understanding broadband speed issue

I've been advised line length is 3.7km by one advisor and 2.1km by another - it may be the first is to the exchange and the second to the cabinet. Thanks for replies ..... Steve
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splovett
Aspiring Contributor
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Message 8 of 10

Re: Understanding broadband speed issue

Same speeds with new HH6A and Draytek 2860n+
Engineer checked with test kit and could see max data rate of 1.8Mbps but actual upstream rate of 0.5Mbps
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splovett
Aspiring Contributor
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Message 9 of 10

Re: Understanding broadband speed issue

Your image shows what I was expecting, in that at the lower end of the spectrum, VDSL uses the sam frequency as ADSL for upstream traffic - up to 138kHz. If that's the case then I would expect to have at least the same speed on VDSL - accepting that I would be unable to benefit from the additional upstream bandwidth allocated to higher frequencies due to distance from the cabinet?
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Distinguished Sage
Distinguished Sage
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Message 10 of 10

Re: Understanding broadband speed issue

True, assuming that the bit loading is the same for ADSL and VDSL at those bins, which presumably it is.

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