Computers have drastically different download speeds on the same network

Question

I have four devices, Windows 8.1 laptop (mine), Windows 10 laptop, iPhone SE, Android phone, connected to the same network and the Windows 8.1. laptop has a significantly slower download speed (~15 Mbps) than any other device (~100 Mbps for the phones, ~120 Mbps for the Windows 10 laptop). Moreover, I also get very different results depending on where I measure my speed while the other devices get almost identical numbers on all websites I’ve checked. Specifically: beta.speedtest.net shows me 170+ Mbps, fast.com shows 70 Mbps, speedof.me (HTML5 based, arguably the most accurate) shows only 15 Mbps. I get the results regardless of whether I am connected through WiFi or Ethernet (tested with multiple cables).

Here’s what I’ve tried to do so far to troubleshoot the problem:

• Making sure that my network drivers are up to date.
• Booting in safemode with network. Same results.
• Checking for bandwidth hoggers. I ran netstat -o and checked each PID to make sure it wasn’t anything suspicious. All PIDs were either Chrome or the antivirus. I tried disabling and eventually uninstalling the latter.
• In Task Manager’s Resource Monitor I checked the processes under Network. All of them are either chrome, svchost, or System, and the numbers look very similar to those I am seeing on the Windows 10 laptop. I also tried running several speed tests and monitoring the number change, and the dynamic was the same to what I observed on the Windows 10 laptop.
• Scanning for malware. Before uninstalling the old antivirus that I had, I ran the scan but didn’t find anything. I then downloaded Malwarebytes but it didn’t find anything either. I am currently in the process of picking a new antivirus. Once I pick one, I will do a scan with it too, but it doesn’t look like it’s malware that it is causing the problem.
• Finally, I tried resetting my network configuration by running netsh winsock reset catalog, netsh int ipv4 reset reset.log, netsh int ipv6 reset reset.log. No effect.

I am at a loss what other software solutions I can try and I am worried that there is something wrong with the NIC or adapter (which can be a pain to change in a laptop). For comparison, my laptop has Realtek PCIe GBE Family Controller and Intel(R) Dual Band Wireless-AC 7260 and the Windows 10 laptop has This Killer Ethernet Controller and Intel(R) Dual Band Wireless-AC 3160.

If you have any suggestions or guesses on what might be going on, please comment. Any input would be greatly appreciated!

EDIT: I discovered that that this is not a hardware issue as I just made a bootable USB with Kali (Debian-Linux-based OS) and running it all speed tests showed 100+ Mbps! This means that whatever is happening, it is a software issue and not a problem with the NIC/modem/any laptop piece.

SOLVED!!! Found the problem! The issue was caused by having the Windows Auto-Tuning feature set as disabled instead of normal. What I did to fix it:

• In command line (as administrator), run netsh interface tcp show global to see if the feature is disabled

• Run netsh interface tcp set global autotuninglevel=normal to set it to normal

Voilà!

Solution

Found the problem! The issue was caused by having the Windows Auto-Tuning feature set as disabled instead of normal. What I did to fix it:

• In command line (as administrator), run netsh interface tcp show global to see if the feature is disabled
• Run netsh interface tcp set global autotuninglevel=normal to set it to normal

Voilà!

Comments

[Admin]

What brand or brands are your network equipment?

[Nyan Octo Cat]

I have Realtek PCIe GBE Family Controller (for wired connections) and Intel(R) Dual Band Wireless-AC 7260 (wireless) network adapters and Hitron CGNM-2250 modem. My laptop is Asus ROG G751JY.

[xenoid]

You can measure slower transfers if there are other transfers going on under the hood (Microsoft updates, etc...). So the first thing to do is to measure your actual laptop traffic. if the router can do this, its best, but you should be able to obtain interface statistics in Windows.

[Appleoddity]

Nice job. Good troubleshooting. Thanks for sharing.

[Admin]

Please post your solution as an answer and mark it, when you can, normally after 48 hours. This will help others that might look for the same problem.

[Nyan Octo Cat]

Ok, just posted. I will be able to mark it in 8 hours. Thank you!

[ScottN]

Holy s***! This was my problem, doing this I went from FileZilla FTP download speeds of < 1 MiB/s to up-to 12 MiB/s.. how does this even get disabled??