XPS 8940, Killer E2600 Ethernet driver issues

@Penwell​ Thank you!

This machine is at my Mom's place in another town.  It will be a few days before I can get down there to make changes.  She will work off of Wi-Fi until that happens.

I'm not totally convinced Killer drivers directly from Intel are any better.  And FWIW, these updates typically only update the Killer Control Panel, not the actual hardware driver for the network adapter on the motherboard. I've had multiple Killer updates on my XPS 8930 but the last time the actual hardware driver was updated was in 2019.  These updates only fix the latest bugs in the Killer Control Panel.

I've had Killer updates (labeled as Intel updates) forcibly installed on my XPS 8930 by Windows Update many times. Every single one of them slowed Ethernet upload speed to a crawl.  I don't have the either the Dell Killer driver or Dell Killer Control Panel installed on this PC.  So that can't explain why updates, presumably directly from Intel via WU, cause the same problem every time.

I just click Start>Run>(type in) services.msc and click OK. When that opens, I set the Startup type for every Killer service (and xTend service, if any) listed to disabled, and reboot the PC. Problem solved, at least until Windows Update force-installs another Intel/Killer update.

@kitsap 

Interesting, I've got an older driver:

I get them all from Intel using the Intel Driver and Support Assistant. Never was offered by Dell Update a new one?

I do have on the System Setting not to allow Driver updates though, and also BIOS Capsule update is off.

My 8940 can use either, wireless or wired. My wireless speed is very close to the wired speed. I have 1Gbps down and 40Mbps up service and the UP is over on both connections by about 10%.

Did you check the Killer app? Under the settings there is Auto Bandwidth that can be set, make sure that is no, and if yes, check the setting, could be limiting it. You can also test the speed when you click on Set Bandwidth, so you can see what the card thinks (if you have not tested that way)? However, that test never matches what my ISP's test is or even SPEEDTEST.NET

Wifi speed seems off though (375 down) and I easily reach well over 700Mbps normally on a 5Ghz band (I assume you are too)?

@Penwell​

Killer Network Service is causing that upload speed issue on the older drivers. Ending that task in the Windows task manager will restore that upload speed, last when I did that for myself. Windows Services control panel you can change there if you want to keep it from starting on every reboot.

The newer drivers from Intel's website correct the upload speed problem, but if you have the Dell drivers installed, you'll need to first uninstall the Killer network suite before installing Intel's (Killer Performance Driver Suite UWD). The Intel network driver installer will state that and stop the install if it sees the Dell driver already installed.

Update,  your recommendation was spot on.  Stopped the Killer Network Service and disabled it so it would not start on a re-boot.  Left the original Dell drivers in place.  Thank you.