I'm having similar issues to you. Poor single-threaded speeds, perfect multi-threaded.

One example: http://www.thinkbroadband.com/speedtest/results.html...

Sometimes the single-threaded speed is more in line with what you're getting, but it's generally this slow

I've been with Zen for ages and it's only gone downhill in the last few weeks. Same problem when I connect a computer directly to the OR modem, so my network/router has nothing to do with it.

Zen are fobbing me off by claiming that this is "expected performance". I know multi-threaded downloads are going to be better, but the difference should not be this great (not to mention that it was fine before).

Between that utter BS, having to repeat things I've already emailed or said, and being asked numerous times to do the same things repeatedly, it's almost as if I am talking to TalkTalk or BT, not an ISP that is supposed to pride itself on its customer service. Requests to have it escalated seem to fall on deaf ears.

All Zen seem to be interested in is running the standard Openreach tests and if there's no problem there, then there must not be a problem - there appears to be no interest in ensuring that there are no issues on Zen's network, having someone from their network team dig into the issue, etc.

It feels as though there's traffic shaping, even though Zen claim they absolutely don't do that. Sometimes a download starts out at a high speed and slowly decays to 1Mbyte/sec or less.

Edited by deleted (Thu 28-Jan-16 16:12:12)

You just described how its like in my case. All i know I'm not going to bother anymore, time to look elsewhere and try...

any chance you can pm me your details and I will try zen tomorrow and provide your cases as another example of the issue to make them acknowledge that there is a fault alas maybe not their fault but within the infrastructure. I mean come one we are paying good money for this and if we are not happy with it then surely there must be something to be done.

It would be interesting to know your packet loss rates.

Even a 1% packet loss rate can have a significant effect on transfer speeds.

Perhaps some packet loss is affecting a singly steam enough to limit effective throughput to 30Mb/s while on an 6 stream test each stream is limited to 76Mb/6 = 12.66Mb/s which is less than half the single stream throughput.

I'm running a ping -n 1000 8.8.8.8 test right now.

The results of the ping -n 1000 8.8.8.8 is

Ping statistics for 8.8.8.8:
Packets: Sent = 1000, Received = 998, Lost = 2 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 9ms, Maximum = 977ms, Average = 12ms

which is pretty good.

there is no packet loss at all

Ping statistics for 8.8.8.8:
Packets: Sent = 1000, Received = 1000, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 15ms, Maximum = 26ms, Average = 15ms

I'm testing remotely using speedtest-cli on Linux and can't see any issues:

sam@340Edenfield:~$ speedtest-cli
Retrieving speedtest.net configuration...
Retrieving speedtest.net server list...
Testing from Zen Internet (82.69.x.x)...
Selecting best server based on latency...
Hosted by Virgin Media (Manchester) [46.75 km]: 16.199 ms
Testing download speed........................................
Download: 67.48 Mbit/s
Testing upload speed..................................................
Upload: 17.88 Mbit/s

Will try TBB speed test later but I have not seen any issues running apple updates, streaming 4k from netflix, speed tests and torrenting.

Quite a heavy user (700GB/month ish)

Speedtest.net likely uses multiple threads. I get flawless results when using it, even though single threaded performance sucks.

Exactly the same in my case Sor

My problem is that I get perfect single thread downloads between midnight and around 09:30 hrs.
for example: http://www.thinkbroadband.com/speedtest/results.html...

But during the working day and evening my ability to download a single thread is totally crippled.
for example: http://www.thinkbroadband.com/speedtest/results.html...

My ping test during the day to 8.8.8.8 lost 7 out of 1000 with a minimum delay of 17ms, average of 20ms and maximum 38ms

I have probably been a Zen customer for around 15 years but their eventual reply to my recent email about this problem left me rather annoyed to say the least!