Upload speed collapsed

[Osirian08]

We recently had an issue on our line fixed and our download speed has now recovered to an acceptable 36 Mbps

However the upload speed has suddenly collapsed today to the lowest level I have ever seen -currently showing 2.29 Mbps on speed tests I have run this evening. This morning it was 6Mbps

Is there some reason my upload speed would suddenly reduce to such a ridiculously low level ?

We are on BT Halo 1 package at the moment 

[chrisjp]

What speed tester are you using? I've used Ookla quite a bit but suddenly it was showing very low upload speeds, while still showing my normal download speeds. So I tried using fast.com and this is showing my normal upload speeds consistently and the same download speeds as Ookla.
I've no idea why this should be, but Ookla is still showing low upload speeds

[Osirian08]

fast.com showing the same result as ookla 

36Mbps down

2.29 Mbps upload

Really cannot understand why it has suddenly  dropped so low.

[Keith_Beddoe]

@Osirian08 

Upload speed is very dependent on the high frequency performance of your line, as that is where the majority of the information is carried. VDSL is optimised for download speed.

If your repaired line is of poor quality, or is unbalanced, then the upload performance will suffer.

Here is a picture showing the frequency usage.

You can see that most of the upload bandwidth is situated 8.5MHz to 12MHz, which is not propagated down copper pairs very well, unless they are of very good quality.

If that spectrum is missing, then its most likely you are using the lower two allocations, hence the lower speed. You may find that restarting the home hub may help, as the allocation may improve.

The broadband availability checker will give you an idea of the expected upload speed, and you may be disappointed at the figures. Upload speeds are never guaranteed on VDSL.

https://www.broadbandchecker.btwholesale.com/#/ADSL