UK ISP Zen Internet Tries to Resolve Network Performance Issue UPDATE –

Broadband ISP Zen Internet has today resolved a problem, which appears to have been occurring for almost two weeks, that caused some of their wholesale partners and related fibre (FTTC and FTTP) customers to suffer from performance problems (e.g. slower than expected speeds, poor latency and high packet loss).
Feedback suggests that Zen didn’t initially appear to acknowledge the complaints from their clients, which left those affected to waste time trying to debug the issue themselves. The customers ended up suspecting that some form of network congestion was to blame.
The good news is that Zen have since accepted that there was a problem, which they say has today finally been resolved.
Mark Howarth, Head of Trading and Partner Experience at Zen Partner, said:
“We are aware some of our wholesale customers faced increased latency as we migrated services from one network to another. Due to this migration, the connections between the two networks caused a shift in traffic which impacted the service for some of our wholesale customers for a short period of time.
Engineering works were performed to balance out the traffic between the two networks and we have not seen any further congestion. We continue to monitor this closely, but if any of our Partners believe they are still experiencing issues, please reach out to your Partner Experience team.”
UPDATE 24th Nov 2022
Feedback from some of Zen’s wholesale partners suggests that the issue has returned.
Not fixed, I’m still on fttc.
If this is the issue that people were getting fixed by asking to migrate back to BT Wholesale then it’s been going on far longer than two weeks.
I’m currently carrying out research on ISP performance issues and hence am looking for additional input.
The report (which is always highly professional) mentions “lower than expected speeds, poor latency and high packet loss.” Simple question “what do each of the metrics identified suggest?”
In short it comes down to network congestion i.e. too many people using what limited resources are available.
Low speed refers to bandwidth e.g. Zen advertise a service with, for example, 900 Mbp/s on average. If a customer is averaging only 100 Mbp/s then it has a ‘low speed’. But, bandwidth is not an actual measurement of speed, it is more a measurement of capacity.
Latency is the time it takes to receive a response from one device to another. Poor latency is a long response time, measured most often in milliseconds. A congested network can see the time taken increase – routers may not be able to handle lots of data packets taking so long to get a response, leading to packet loss i.e. network packets are unable to be processed so they are not.
Others can probably explain parts of this better & Wikipedia is your friend
I’m not sure I understand the question. What could be causing those metrics to be poor? What are the metrics?
I have to admit it’d be quite entertaining seeing a comment from here in a citation.
Speaks of utter incompetence though. Engineering should have been all over this monitoring capacity during the migration. Even something rudimentary like migrating test lines first, then monitoring their behaviour during use whilst the migration took place.
If it isn’t incompetence it’s arrogance and trying to do this without the necessary capacity (or being cheap) and thinking they wouldn’t get caught out.
The fact they think 2 weeks is a “short period of time” would massively concern me if I had any dealings with Zen.
Seems par of the course for Zen
Every so often when the forum threads are a light with complaints about Zen’s poor performance they get Mark to write an article saying they have found and fixed the issue on their network. The fact they haven’t found and fixed anything seems unimportant to them, why don’t they stop this BS and fix the issues. Some people have been having major issues isn’t the beginning of this year and Zen are clueless how to fix them.
I agree – there are often complaints about Zen, and I know of people using ISPs using Zen Wholesale who left those ISPs because of the issues they had (not that I’ve seen them except once a few months back for a short time) but Zen has a massive network capacity issue or some epic misconfiguration, and absolutely haven’t gotten to the bottom of it. They seem utterly clueless on what is wrong or how to fix it.
It isn’t new, isn’t fixed and isn’t some recent issue as the complaints never stop flowing and often from pretty clued up people.
Zen didn’t order me to write anything, that’s not how ISPreview works. We received complaints from several customers and wholesale partners, which appeared to exhibit the same trends. We gave Zen a deadline to respond to those concerns, and Zen managed to fix it before that time (they were already working on a fix by the time we asked). We then waited to see if those reporting the issues would see an improvement, and early feedback seemed positive. The article was published.
I must stress that this is mostly focused upon gripes coming from a number of those taking wholesale services and related tails from Zen, including FTTP/C customers on those partners.
I should also add that congestion/capacity issues can be specific to a location or certain users and most ISPs will have a few of them at one point or another, so this article isn’t saying that Zen has fixed all such issues, just the one that was reported to us by several parties.
@Mark, my comment was not meant to reflect badly on you 🙂
I have noticed that Zen are always quick to tell you (aka ISPReview) everything is fixed when the truth is nothing normally is. I remember previously their network guys calling an affected customer to say they was having a management meeting the following afternoon to decide how to progress an ongoing (3 month) issue affecting dozens of customers but at 08:00 the following morning you had already published an article that the issue was resolved when the same users were still having issues.
To say I don’t believe Zen is an understatement.
You need to point me to the bit where Zen said “everything is fixed”.
They had a specific issue that started 2 weeks ago, they fixed it, they announced they fixed it and Mark reported in it.
This has nothing to do with the ongoing issue with Ultrafast FTTP customers on Zens (Openreach) GEA Plexus network.
In other words the issue where users get full speed through BT Wholesale but those speeds drop considerably when Zen migrate users from BT Wholesale to GEA (their own backhaul).
That issue very much still exists.
Zen don’t seem to care much about it with customers simply being migrated back to BT Wholesale or being allowed to leave penalty free.
And you need to point me to where I said it was.
I use a smaller provider who uses zen as there main carrier.
Ive been having issues with Zen for months, fluctuating ping and packet loss.
Zen have been going down the toilet for years now, used to be good, now they’re make Vermin Media look good!
Vermin you say that word reminds me of Jeremy Corbyn.
They initially told me it was my doorbell that was causing the problem.
Then they said it was the wiring to the telegraph pole.
I left Zen over a year ago when their service was still pretty good. Since then, I’ve seen the poor reviews and complaints shoot up on here and other places.
Even if a fair number of those aren’t justified (and believe me, some people will bitch about anything) there’s no smoke without fire so it looks like I got out just in time.
I suspect that this is directly due to the expansion of the company. It seems to be a law of nature that when a company starts to become large, as Zen are becoming, their quality and customer service drops significantly. Shame, as I don’t have anything bad to say about the service I received from them. I just needed certain things that they couldn’t provide.
This gives me even more confidence in ISPs who still have data transfer caps (I won’t name names to try and avoid awakening the trolls) and semi-deliberately remain small.
It would appear that my earlier comment caused some confusion, for which I sincerely apologise. In a nutshell, I’m carrying out research into the definition and collective understanding of Internet metrics, and in particular:
1.Speeds (access net only?)
4.Traffic Management (Inter domain)
5.Congestion Control
If anyone wishes to contribute to this piece of work, can you please em me with your thoughts at
I will of course preserve anonymity in my paper, but I am happy to circulate the output for those who may have an interest?
I have a standard fttc service with zen and they aren’t very good at all.
The latency is an issue, as is their odd routing of traffic between London and Manchester where if you go to Manchester it is awful as it adds extra hops.
The customer service is terrible, with the odd good point, but you can be on hold for extended periods and emails have taken a silly amount of time to reply.
I stay because of the £29.99 fixed price inc line, and hoping fibreheroes hurry up as they have just started the planning phase.
I would advise no one to go to Zen, they are living off their past glories.
I’ve been with zen for ~10 years and I would no longer recommend them.
The difference between their London and Manchester gateways is beyond a joke and having had to deal with them recently on a fault (no service) that lasted over a week they were absolutely useless. I ended up having to contact OpenReach myself directly to get things resolved.
My router’s Speedtest is about 10% of what I should be getting – about 33-40Mbps (previously I was getting about 300Mbps down). My uploads are fine – 48Mbps.
So whatever is happening, I don’t think it’s resolved!
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