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after leaving the client open for 2-4 hrs with my torrents seeding or either downloading.

my network card hits the fan.

i am on a 1gig down/up network it goes to 100-300mb/sec cap with cpu usage going 50-80% when i run speedtest , there is high DPC latency issues with ndis.sys .

rebooting the pc fixes it again for 2-4 hrs.

and yes i tried using another torrent client other than qbitorrent and the problem is gone.

qbittorrent is doing something w/ the windows system network files / interface etc.

waiting for a fix to this.

I have the same issue. After updating to Winver 1903 (OS Build 18362.175) and while torrenting using qBittorrent the computer would start stuttering, disconnect from the Internet entirely, or the connection would become very unstable. Disabling and enabling the Ethernet adapter would resolve most of the issues but the connection would be relatively slow. The only real solution seems to be to reboot the computer every time this happens.

I am using qBittorrent v.4.1.6 with a KillerE2400 Gigabit (2.0.2907 driver) and my router is a Linksys WRT32X. The Killer Control Center has been uninstalled as people seem to dislike it in general. Another thing is that I run BitDefender. At first, I thought it was BitDefender that kept scanning every access, but I put the torrent folder as an exception, but the problems still occur.

Have done my best to clean up any startup applications and services, but I have been unable to isolate what would cause the problem since it doesn't seem to appear until after the computer has been idle for a while, usually it happens after I wake up and start torrents in the morning.

It is quite strange as qBittorrent was running fine before the windows update and I would get speeds that amounted to almost half of my gigabit connection. Now, the fastest download speed is equivalent to a 100Mbps connection (under 10MB/s).

Just a follow-up. Today I downgraded to qBittorrent 4.1.5 and it seems to have resolved the biggest issues with computer stuttering, losing Internet connection entirely, and even crashing the computer.

However, I am still unable to reach gigabit speeds (used to be able to get to the equivalent of 300Mbps, but right now it seems capped at around 100Mbps), but at least my computer isn't unusable or losing Internet connection.

EDIT: Nevermind, it went back to disconnecting me and all that jazz. I would assume that this doesn't have anything with qBittorrent but is mainly a problem of Windows 1903.

Same problem here after the Windows 10 1903 update.
Updated every driver that was outdated, espcially the network drivers.
Problem was the increase of the nonpaged pool. When looking for the source (task manager, details) the only proces that was steadlily increasing the nonpaged pool was Qbittorrent. A long time I used Qbittorrent 3.3.16, but after these problems I updated to Qbittorrent 4.1.6. Problem was not solved and still Qbittorent steadily increases my nonpaged pool till my memory is reaching 90/100% and everything 'hangs'. Without the use of Qbittorrent I have no problems, so for me the problem is Qbittorrent after the 1903 update.

By the way, just went back to version 4.1.5 but the problem stays the same. No difference. My nonpaged pool is steadily increasing from the moment I start up qbittorrent.
Looking forward to see more replies to this topic ;-)

waiting for an official response from qbittorrent peopel on this

Just found out that my problem is not qBittorrent but Bitdefender.
With Bitdefender completely uninstalled now qBittorrent runs smoothly.
My nonpaged file is not increasing anymore and is stable.
So my memory problem is solved at the moment. Waiting on a Bitdefender solution instead.

Was browsing around in other threads. I think I may have found my solution.

Basically, Killer's network stuff is terrible. I re-installed the drivers but it did not help. It turns out that I had to disable the Killer Network Service.

If someone is looking for the same thing, just start services.msc and find the service, stop and disable it.

Problem is solved, for now, anyone who cares.

Problem was with Bitdefender at least for me ( if you are having a problem and using other than Bitdefender then its the antivirus/security software)

Bitdefender will make a software update soon for auto fix, but you should contact them via ticket/email and get the fix by email.

using qBitTorrent on windows 1903 did something with Bitdefender itself that caused this problem. But I am sure other software using internet b/w would do the same.

Thanks to everyone, it took 3 weeks to find the problem and 1 more week to get it fixed without uninstalling Bitdefender.

Also just for information if you have 1gbit upload as well, windows 1903 is some way capped to 500mbit/sec upload. This problem itself is a microsoft flaw and they have a lot of tickets on their dev forums.

It is not your lan card or bad drivers , its 1903 windows fuck up they released without testing