I used the instructions here:
https://myrandomtechblog.com/cryptomining/change-mtu...

Mmm not convinced on high resistance fault. Why? Upload sync would have decreased with a resync if errors were so bad that a 16000 Kbps sync was only carrying 50 Kbps of upload traffic.

Completely agree.

I have a pet theory that a series of repeated GEA FTTC tests, run very close together will often eventually produce a �potential HR� test result .... thus allowing CP CS to generate a non appointed fault.

This is borne out by VERY often seeing the HR test result on faults, but not being able to repeat it when running the same test on the same system later.

My money is on the OP�s visit returning �fault not found� *



* Or an outside bet might be a duff port on the DSLAM, though a hunch says not.

Edited by Zarjaz (Thu 21-Nov-19 07:15:32)

I have now solved my problem so I thought I should post the 'cure' in case anyone else has the same issue.
Between my successful upload on Saturday and my failing upload on Tuesday I had installed Kaspersky Free Cloud version 20.
Wondering if this was the culprit I uninstalled it and installed the non-cloud version 19. Unfortunately this still didn't fix the problem.
I then downloaded the Kaspersky remover program (kavremvr.exe) and ran it twice (the first run I selected Kaspersky Free version 19 and the second run I selected Kaspersky Free version 20). I rebooted when prompted.
I ran the upload and it worked normally.
I then reinstalled the non-cloud version 19 (which automatically updated to version 20).
I ran the upload again and all is back to normal.
I have no idea what caused this problem but it would appear to be something in Kaspersky Free Cloud.
I have also turned off Secure Connection though whether this has any impact I do not know.

In reply to a post by PeterWorks:

I have now solved my problem so I thought I should post the 'cure' in case anyone else has the same issue.

I asked in my first post if you had any security software (and which OS).

Yes, security software in 2019 on Win10 or macOS is mostly a problem itself. By trying to protect people, the security products are having to change the operating system in the same way as malware does. In at least one case this has stopped windows patching and left people exposed, whom wouldn't be exposed if they didn't run the third party software.

We live in interesting times.

So, Openreach engineer tested the line and advised.... fault not found. Unfortunately I wasn't here to show him exactly what the problem was, i.e. download speed stayed at around 50-60Mbps throughout, only upload speed was affected, though this probably wouldn't have mattered as the problem obviously wasn't the line.

The problem seems to have miraculously resolved itself, i.e. Plusnet have finally fixed it at their end.

No acknowledgement from them though.

Thanks everyone.