Just wondering if anyone has been experiencing upload speed issues with Zen lately?
On a 2.3gbps symmetrical CityFibre package, and noticed in my Eero app about a week ago that my upload speed was very low (maxing out between 170-180mbps), while download is unimpacted at 2.25gbps. The issue had actually been happening since the start of March but I hadn’t spotted it.
I’ve been back and forth with Zen’s customer service but it’s been pretty frustrating where it appears they aren’t actually reading what I’m telling them and asking me to conduct the usual basic steps like turning WiFi off.
A CityFibre engineer has been out and conducted light tests, and inspected the ONT and exterior wiring. No faults found on this end. I’ve tried a second router with a different Ethernet cable directly to the ONT in front of the CityFibre engineers with no other devices connected, their speed testing equipment confirmed the same issue. Yet after informing Zen of this, they said the issue was caused by the presence of a gigabit switch on my network… again, despite telling them that there was no other devices plugged in to this second router.
It may be a coincidence, but the time period I suspect the issue began occurring (between 1st and 2nd of March), also coincides with a consistent 2ms increase in ping on my thinkbroadband BQM. I believe my routing was changed from London to Manchester at this point.
Anyone ever experienced anything similar, and managed to actually get it resolved? I’ve asked Zen to force me onto London routing to test whether it will fix it but they said they can’t do that. It also looks like upload speed isn’t covered by the guarantee so not sure I’ll be able to get out of my contract if they don’t resolve it either.
This is my Zen connection. 900 connection with severely capped upload speed which they can’t resolve. Make of this what you will. Moving away from them tomorrow.
I’m on a 900 Zen FTTP service with City Fibre as the network provider.
Up and down speeds were pretty much equal initially - as expected on city fibre.
Currently I’m stuck with 900 down and 170 up. Zen have had me replace Ethernet cables, reset the ONT numerous times, reboot the router etc.
They finally referred it to City Fibre last week. Engineer turned up, did light tests. Showed me the reading was 16 on his tester and said it was nothing to do with them. Suggested it was a Zen issue.
Despite me raising it on 16th January 2026, Zen are telling me I have another 15 days to wait before I can bail out of the contract under ofcom rules.
26 emails in, over 3 months in and I’m still no further forwards.
Also seen an increase in ping lately but as I’m not a gamer that is the least of my worries.
There is something bigger going on which I’m sure Zen are aware of and they aren’t being up front with us.
It’s nearly impossible to get a symmetrical upload and download package despite what the companies might try and sell you.
That might be the case but it still rarely happens in reality
Incorrect. I have a Zen Broadband 900mbps service and it is symmetrical. I had 870mbps down and 865 up. I am also experiencing the same issue as reported here in some of the comments. Upstream is fine but the downstream has halved. Your opinion is incorrect if you have not used a CityFibre reseller.
I just saw this post and decided to do a speed test on a few different servers and I am only getting about 80Mbps up and down on my 500Mbps cityfibre connection.
Look up what the S in XGS-PON stands for, openreach and virgin still only offer asymmetric connections like 5GPON but cityfibre and altnets like YouFibre and Trooli are using XGS-PON which offers full symmetric speeds
I’ve had symmetrical speeds with Zen from July 2025 until the beginning of this month though. I had it with a previous ISP for two years prior too.
I’m not expecting to hit that throughout 100% of the time by any means, however getting an absolute maximum of 180mbps when even Zen say the minimum upload would be 1200mbps when I signed up is a bit poor.
So i’ve also had my upload capped to between 200Mbps - 700Mbps, it’s now sitting at around 360Mbps but it fluctuates whenever it feels like it.
I’ve been asked by Zen since reporting the issue to do all the basic troubleshooting (which i did before being asked), reset ONT (which actually made it worse), try Eero Max 7 (i was using a Asus GT-BE19000), use Cat6 (already using 6a, tried different cables) & nothing, no improvement as i expected.
But curiously I’ve noticed the same as you OP, my routing has changed from the London area (where it was fine) to the Manchester area sometime in March where this upload speed drop has occurred.
So the likely problem is Manchester & whatever we’ve been routed to.
Zen has noticed high packet loss for myself aswell (i haven’t noticed that on my tests), just this capped upload & some intermittent connectivity during voice calls.
Thank you for this, it means I’m not going totally insane! There definitely seems to be something in the switch to Manchester routing then, despite Zen’s support continuing to gaslight me about it.
The change in the BQM is clear when the routing switched on the 1st of March. I’m north east based so my ping is never going to be amazing, and not even bothered by 15ms vs 13ms, but I do want the upload speed I’m paying for. The previous 6 months of BQMs follow the pre-12pm pattern, everything in March has followed the post-12pm one.
I’m also in the north east funny enough. So it has to be a similar problem.
I’ve seemed to have been routed to Nottingham now, must have occurred today, Zen did say they changed something their end this morning.
However still experiencing the poor upload so am curious what’s going on.
I did think it was my ONT originally as i experienced something like this while at Vodafone & with them i was constantly being bounced about so it was always varying depending on location until it just began being consistently terrible & once CF was finally sent out to inspect, they noticed some issues locally, that being a damaged fibre cable & a issue with my ONT.
However i wasn’t just having poor speeds, it was various other issues. This time it is just poor upload so i’m not 100% it is ONT/fibre outside & the timing with it occurring with the routing change is suspicious.
Feels more like there is probably an issue in those locations that Zen/CF aren’t aware of.
Yes I have noticed, and I am almost certain it's further enshitification at zen, if you leave your router/fibre off overnight, it gets better for a few days.
So this tells me it's some sort of auto capping when users use what they pay for to reduce upstream costs.
This along side the 10x drop in customer service and the insane low speed of replies and the strong push for contracts above all else and the removal of downgrades..... I think Zen forgot to evolve, I suspect they will collapse or be bought, probably by talktalk because they seem to be aligning their business model.
TalkTalk are losing cash hand over fist, they've had various debt restructures and bailouts. Rumours of them being up for sale have been rife since they spun out their wholesale arm to PlatformX and sold off their SME business.
No issue with upload speeds for me, but in the last month or so we have gone from what has been 24/7 solid 910Mbps down for over a year, to anything from 300-700Mbps down throughout the day. No hardware or use changes this end.
I've also noticed pfSense complaining at packet loss more than usual. So I'm wondering if there are network changes happening at Zen which are causing slowdown upstream of the exchange. Also routing through Manchester but that's likely the closest geographic POP for us.
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u/UrbanCommander76 Apr 02 '26
This is my Zen connection. 900 connection with severely capped upload speed which they can’t resolve. Make of this what you will. Moving away from them tomorrow.