capacity issues - continued

[#1]

No, I don't...
It's been consistently unable to sustain the full throughput for a good while now without any changes at my end to account for it...
I wouldn't completely discount issues around the TBB tester itself, but I'd need to do some separate testing with full control over both ends and I haven't had the time for it...
So just a suspicion for now.          (EDIT: Based on the fact that I also only get 15Mbps out of SFTP uploads.)

[#2]

Quote from: Anotherone

Afraid not, that was hop 3 so drawing any definite conclusions is a no no..

Sorry, I just jumped to hop 3 and ignored hop 2 because of it not showing a hostname and just an IP.
If it's of any interest, any service that can identify my IP is showing up as a BT IP. That's the first time I've had that on PlusNet, usually I get IP's that are PN or InfoNet

[#3]

Quote from: Anotherone

Is it more likely that 195.166.130.220 is a pcl one?

I think 195.166.130.220 is ptn-bng01, and the bit with link1-central10.pcl-ag07.plus.net is wrong (out of date).
We can try comparing traceroutes:
[tt]traceroute to 195.166.130.220 (195.166.130.220), 30 hops max, 60 byte packets
1  gateway (192.168.0.1)  3.534 ms
2  lo0-central10.ptw-ag01.plus.net (195.166.128.195)  24.049 ms
3  link-a-central10.ptw-gw01.plus.net (212.159.2.144)  24.330 ms
4  xe-4-2-0.ptw-cr01.plus.net (212.159.0.240)  23.860 ms
5  195.166.130.220 (195.166.130.220)  26.958 ms
traceroute to 195.166.130.191 (195.166.130.191), 30 hops max, 60 byte packets
1  gateway (192.168.0.1)  1.423 ms
2  lo0-central10.ptw-ag01.plus.net (195.166.128.195)  23.430 ms
3  link-a-central10.ptw-gw01.plus.net (212.159.2.144)  23.982 ms
4  xe-4-2-0.ptw-cr01.plus.net (212.159.0.240)  29.208 ms
5  lo0.11.Central11.ptn-bng02.plus.net (195.166.130.191)  24.258 ms
traceroute to 195.166.130.178 (195.166.130.178), 30 hops max, 60 byte packets
1  gateway (192.168.0.1)  1.334 ms
2  lo0-central10.ptw-ag01.plus.net (195.166.128.195)  29.101 ms
3  link-a-central10.ptw-gw01.plus.net (212.159.2.144)  28.766 ms
4  xe-4-2-0.ptw-cr01.plus.net (212.159.0.240)  22.834 ms
5  ae1.pcl-cr01.plus.net (195.166.129.1)  23.467 ms
6  lo0.11.Central11.pcl-bng04.plus.net (195.166.130.178)  23.868 ms[/tt]
The route to 195.166.130.220 from ptw-ag01 is the same length as to ptn-bng02 (I didn't have an IP for ptn-bng01 handy), and pcl-bng04 looks further away, which suggests 195.166.130.220 is in Telehouse.
@NoZephy
The IP address showing as BT is probably one like this, Plusnet fairly recently started using those ranges of IP addresses, some things showing it as BT shouldn't cause any problems.

[#4]

Ignore me 

[#5]

Happy to report that, in my case at least, whatever was done has fixed the single/multi thread problem and I'm now getting good results 24/7.
What I thought was the issue getting worse after the fix turned out to be a switch on my network coincidently going bad with the same symptoms!