Question Slow upload speed on entire network when PC is turned on

Apr 6, 2022
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So over the past few months, whenever my PC is turned on, the upload speed on the entire network tanks after around 5 or so minutes. Normal upload speed for us is ~40Mbps, and when the drop occurs it falls to ~1 or less, across all devices. However when the PC is off, the network is stable. I try and stream to Twitch which is why I noticed the issue.

I've completely reset my PC, cleaning the drives completely in fear of some hidden malware being the issue. After that didn't fix it, I bought a brand new NETGEAR R6700AX - AX1800 router (had an old router anyway) and the problem is still occurring. I tried plugging in directly from the modem, and still saw the same upload speed drop when bypassing the router. I've changed things like: DNS settings, Large Seed Offload, Delivery Optimization, and other settings trying to resolve the issue. ALSO, it occurs when both hardwired using ethernet (which I've changed cables twice :( ) , and when using the Intel WiFi 6 card I have in the PC as well.

My ISP says it's something on my side, as they show stable speeds also.

I have:
OS: Windows 11
Motherboard: ASUS TUF X470-Plus Gaming AM4 ATX
CPU: AMD Ryzen 5 3600X
WNC: Intel(R) Wireless-AC 3168 Wi-Fi 802.11ac DualBand
 

Lutfij

Titan
Moderator
Welcome to the forums, newcomer!

What BIOS version are you on for your motherboard? Where did you source the installer for your OS? See if your router has any firmware updates pending as well.

across all devices.
What other devices are in your household connected to the ISP's end?
 
Apr 6, 2022
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Welcome to the forums, newcomer!

What BIOS version are you on for your motherboard? Where did you source the installer for your OS? See if your router has any firmware updates pending as well.

across all devices.
What other devices are in your household connected to the ISP's end?
Thanks for the welcome :)

To answer your questions in order:
BIOS Version/Date : American Megatrends Inc. 5007, 6/17/2019

My Windows 11 install came from Microsoft. When I did my PC reset, I chose to reinstall my image from the cloud. I originally did my Windows 11 install from the Updates section in settings once it became available a few months ago.

Firmware for router is up to date. It's also new, I purchased it to see if it would resolve my issues lol.

We have many devices connected to the internet: roughly 10 based on my nighthawk app. I've only ran a speed test though on our personal laptop and an apple iphone both connected to the network to check speeds there when the drop is happening. The other devices are things like our smart tv, nest thermostat, security system and such. I haven't noticed a drop on those devices as our download speed remains stable, only the upload speed is affected (once the PC is turned on).
 
Apr 6, 2022
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I've put details of a test I just ran today just using speedtest.net. I updated the BIOS since we spoke about it above but that didn't seem to fix the issue either. Before the PC is on, my upload speed is around 40 like mentioned above. I wouldn't think it would be an issue with my wifi/ethernet port since it occurs on both.


PING ms
35
DOWNLOAD Mbps
473.25
UPLOAD Mbps
2.05
 
Apr 6, 2022
6
0
10
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I've put details of a test I just ran today just using speedtest.net. I updated the BIOS since we spoke about it above but that didn't seem to fix the issue either. Before the PC is on, my upload speed is around 40 like mentioned above. I wouldn't think it would be an issue with my wifi/ethernet port since it occurs on both.


PING ms
35
DOWNLOAD Mbps
473.25
UPLOAD Mbps
2.05
Another update:
I rolled back to Windows 10 thinking maybe something was wrong there. I updated my drivers/chipset for the network adapters/motherboard and still no dice. Upload speed is perfect until my PC turns on… I’m at a loss!
 
This is actually very hard to do even if were to try to do it intentionally. Networks are designed to prevent devices from seeing other devices traffic.

The only 2 things I can think of that can cause this is some kind of IP conflict or the pc sending lots of traffic and using all the bandwidth.

If you are using the defulat DHCP method of getting a IP from the router it is unlikely a conflict. It mostly happens when you set it manually.

Watch the resource monitor network tab and see if there is any traffic running, I would leave all the browsers closed with no app up other than the resource monitor for the first test. You should not see much running at all on a idle machine. Sometime windows update causes issues but that would be download and not upload traffic.

If you get desperate try a linux USB boot image. This will not change your hard drive windows install. This will eliminate anything in windows or any software installed. Unfortunately it won't tell you what in your windows install is doing it.
 
Apr 6, 2022
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This is actually very hard to do even if were to try to do it intentionally. Networks are designed to prevent devices from seeing other devices traffic.

The only 2 things I can think of that can cause this is some kind of IP conflict or the pc sending lots of traffic and using all the bandwidth.

If you are using the defulat DHCP method of getting a IP from the router it is unlikely a conflict. It mostly happens when you set it manually.

Watch the resource monitor network tab and see if there is any traffic running, I would leave all the browsers closed with no app up other than the resource monitor for the first test. You should not see much running at all on a idle machine. Sometime windows update causes issues but that would be download and not upload traffic.

If you get desperate try a linux USB boot image. This will not change your hard drive windows install. This will eliminate anything in windows or any software installed. Unfortunately it won't tell you what in your windows install is doing it.

Hmmm, I may have to try that last one.

I am using DHCP also. I may have something hardware related going on, I'm not sure what would cause it to occur on both ethernet and Wi-Fi though if that's the case.

I ran a test today before I turned the PC on and we were getting 42Mbps up, now with the PC on it's at ~2 again. And the resource monitor shows hardly any traffic, especially in terms of sending information. I did a clean install, so only apps on here right now are discord and the basic Windows apps.

Could there be some interference with my PC and another IoT device on the network?
 
Likely all your devices are only talking to the router. You would see open session in the resource monitor if it was talking to other devices in your lan.

When they talk to the router or anything on the internet the traffic only goes between the router and that one device. It is not sent over any other cables.

You could load wireshark on the machine and capture all the traffic. You would then see if there was any strange traffic.
 
Apr 6, 2022
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Likely all your devices are only talking to the router. You would see open session in the resource monitor if it was talking to other devices in your lan.

When they talk to the router or anything on the internet the traffic only goes between the router and that one device. It is not sent over any other cables.

You could load wireshark on the machine and capture all the traffic. You would then see if there was any strange traffic.

True, I may try Wireshark as well... it's very difficult to pinpoint since I've tried so many things.

I won't mark an answer yet, but if I ever figure it out, I'll be sure to come back.
 

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