Hi all,
So we’ve had at least 10 customers roll back Windows update and this has resolved the issue fully. Please try and report back.
Can’t do that on my work laptop unfortunately…
The KB that was posted on this thread was only relevant to Windows 11 I think. I don’t have any Windows 11 devices so don’t think this is valid for all. Running test direct on my UDM, speeds are around 200-300Mb less than before migration. Uploads completely unchanged.
Plus, @mikekilley above was running on a Linux box and having same issues.
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Surely running a speedtest directly from the router rules out the Windows element?
Speedtests directly from the router are still lower than before migration.
I find it hard to believe that the KB I saw listed (a .net update) would cause slowness of the networking.
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Sorry @Yayzi_Team, but I have to disagree with you telling customers to roll back any Windows updates. The only company that should be advising that is Microsoft. If this was in some way caused by a Windows Update, I’m sure we’d have heard about it by now as it would be affecting Windows users globally. Roling back updates means compromising on security patches etc.
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Have to disagree with you here, MS mess up updates all the time.
This is a .net patch that’s being rolled back, if it fixes the issue then it can be reported to MS who will then re issue it without the bug.
Happens all the time. Customers choice then to roll it back and fix issue or not roll it back and wait, if the later then its not yayzi’s issue.
Yes they do, but something like this would have been heard about by now surely globally, do you not agree? And not just by a few customers of an ISP that happened to have done a hardware migration recently? Far too localised of an issue to put it down to a Windows Update alone. And that doesn’t explain the results I’m getting on my Linux box. Not convinced, sorry.
It seems the Impacted update is only KB5048162 which is for: 2024-11 Cumulative Update Preview for .NET Framework 3.5 and 4.8.1 for Windows 11, version 24H2 for x64
If you have 2024-11 Cumulative Update Preview for .NET Framework 3.5 and 4.8.1 for Windows 11, version 23H2 for x64 - KB5048163, you won’t be impacted it seems
Rolling back this update on 24H2 seems to fix the issue and it was an ‘optional’ update anyway, it won’t impact security in anyway as the update was not mandatory
I will be installing a virtual machine to test with tonight
So here’s my results:
Removed KB5048162 as advised:
Rebooted my PC and on running speed tests again:
Yep, no change whatsoever…
I’m going to put this out there, but your comment is the only one I can find on this site which specifically mentioned that particular update KB number? Where else has it been mentioned? The only things that @omar said was that he “roll back windows update” (sic) and “did a fresh windows install”, I don’t see any other mention of which update…? 
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All my machines are fully up to date (Win11) and I don’t see speed issues at all…
Sorry @Yayzi_Team, but thats not the issue here.
First of all check if this is indeed the cause of your lower speeds with (from an administrative command prompt):
netsh int tcp show global
and you should get:
If this says ‘disabled’, then that’s the cause of your slow internet speeds.
I had a try of this earlier and set:
netsh int tcp set global autotuninglevel=disabled
and all my internet speeds went right down from 1500Mbps to 150Mbps (dl and ul), that’s quite a noticeable change. Setting this back with:
netsh int tcp set global autotuninglevel=normal
brings me back to the current status of still having reduced speeds, although not as dramatic as that change made it.
We need to stop thinking this is purely a Windows issue, as my tests on Linux have already proven this to be the case.
Same here:
Perhaps there are 2 issues, one described with the update causing especially slow speeds and one I have with around 200Mbps loss.
I still maintain that any Windows issues are irrelevant when doing speed tests directly from the router! So for myself and others like @mikekilley - the Windows issues are not our specific issue.
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I don’t disagree with you guys, on testing from the router obviously wouldn’t have anything to do with the Windows updates.
We are still looking into all possibilities and like you said a couple of issues here.
Majority have indeed been resolved with the Windows rollback…we will continue to look into the other problems.
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Yeah, mine’s around a 200Mb drop too, which is interesting.
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Mine seems to be a problem with compatibility of my Unifi kit and the backend which I didn’t have before migration. When I plug the PC directly into the ONT, I’m back at full speed. I’m trying different MTU settings currently and testing - but don’t hold much hope I will find the fix this way.
We’re using the same kit as we did previously. Just with more capacity, peering etc… but the core router we use is the same. We also have plenty of people using unifi without issues. So if you do identify a particular issue please share it might be helpful to others 
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Bit tricky for me to plug a PC directly in to the ONT. I could try a laptop but it would have to use a USB 2.5Gb adapter and I don’t know if I’d get full speed on that. But yeah, I’m Unifi and I’m about 200Mb short just like you so it is quite intriguing.
If I have the time and capacity, I might fire up my Opnsense VM and see how that fares.
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