Very low upload speed, download speed normal

[MLIT]

This started about last week; no changes have been made to any of the switches. We're a small business so not very many employees, but we're a TV station so we have multitudes of servers.

Our Primary ISP is a 2gig by 2gig connection, same as our Secondary backup ISP. On any given workstation we would normally see about 400+ download, and 300+ upload. Currently, I'm seeing only 0.15 upload speed average on affected workstations. My workstation however is perfectly fine as well as some others.

We have two separate buildings on the property. Each building as a switch stack of 9300's, connected by etherchannel on the tengigabit ports via fiber. I've tried a number of things I know to troubleshoot but am still at a roadblock. I contacted our Primary ISP who verified no issues. We have some workstations in each building affected by low upload speed; we also have workstations in both buildings that are completely fine.

One thing I did try which resolved the problem for one workstation, a Dell XPS 8930, was plugging in a USB to Ethernet dongle. This ultimately gave that workstation a new mac address. I haven't the slightest clue why this would fix the low upload speed for this workstation.

I appreciate any assistance you may offer.

[MLIT · Accepted solution]

Please disregard this post.

I randomly discovered that the Killer E2400 Gigabit Ethernet Controller's have an issue with upload speeds. Disabling the Killer Network Service fixed my problem.

[balaji.bandi]

I do not see any reason switch side has this issue, May be you can try below steps on the switch side.

1. check the stack ring ok ?

2. if the switch up for Long try reboot and check. (in maintenance window)

3. IOS XE 16.8 is quite old upgrade to latest 17.9.X stable version

Device upload issue :

1. check on port side what kind of negotiation and any errors on the port connected.

2. try connect the device in different port and asic and test it.

3. try any test device with latest drivers on the NIC PC use for testing.

testing's :

is the ISP Links connected to both the Buildings or only 1 Building.

what is the commonalities of upload issue device  ? OS / Compute specs/ Ethernet cards - compare to all working as expected devices/server 

any antivirus (disable and test it)

[beaven67]

If anyone encounters a similiar issue on the 9300 series switches. Check the firmware version. I was running 17.06.03 and upgraded to the latest version and it fixed the issue! I was getting 2-5Mbps uploads out and normal downloads and i cannot believe it fixed it. You never know how many "Silent" fixes there are in firmware these days!!