Upload Speed Dramatically Dropped

I recently did an internet speed test and I am receiving 5% of what my expected speeds would be. My last speed test was 850Mbps Down and 50Mbps Up. I have a symmetrical gigabit fiber connection. I am a level 2 support technician and I have tried everything I can think of to fix this issue including but not limited to:

Calling the ISP and confirming the connection is 1000/1000 on their end
Testing the network speed on another machine (result was 920/940)
Restarting the router
Connecting using another cable
Installing the latest network drivers from the motherboard manufacturers website
Checking windows update for latest updates
Uninstalling the driver and reinstalling
Spent hours on google researching this issue and trying 20+ fixes
Restarting the machine multiple times
Running speed tests from different speed test sites (all similar results)
Disable any QoS services/applications
Swapping what port the machine is connected to on the router


Relevant Information:
Windows 10 21H1 OS Build 19043.2006
2.5Gbps LAN port
Symmetrical 1Gbps Fiber To The Home Internet Connection

I have no idea what is causing this issue and at this point I am clueless on what to try next. Any suggestions are welcome

Hello

I would first start off with these things.

1. Disabling IPv6 in the network adapter options.
2. Open command prompt, type 'ipconfig /flushdns'
3. Command prompt again, type 'netsh', then type 'wlan', then type 'winsock reset'

Reboot machine. See how you get after that. Let us know.

Pluginz said:

Hello

I would first start off with these things.

1. Disabling IPv6 in the network adapter options.
2. Open command prompt, type 'ipconfig /flushdns'
3. Command prompt again, type 'netsh', then type 'wlan', then type 'winsock reset'

Reboot machine. See how you get after that. Let us know.

You are truly exceptional, it worked and I am back at regular speeds. I am unfamiliar with those commands, what was the issue and what did those commands do to fix this issue?

Hey bud thats great news and glad you back to normal.

Okies well for me its just a case of process of elimination. Theres two Internet protocols working along side each other, IPv4 and IPv6. Now that you have disabled IPv6, flushed the DNS cache, reset the network adapter, rebooted and its working as normal, suggests to me that there is either a problem with security permissions within the network adapter driver files, or, your ISP does not support IPv6 yet.

If you can, get hold of your ISP and ask them whether IPv6 is fully supported on their network. Chances are probably not.

Hope that helps

Pluginz said:

Hey bud thats great news and glad you back to normal.

Okies well for me its just a case of process of elimination. Theres two Internet protocols working along side each other, IPv4 and IPv6. Now that you have disabled IPv6, flushed the DNS cache, reset the network adapter, rebooted and its working as normal, suggests to me that there is either a problem with security permissions within the network adapter driver files, or, your ISP does not support IPv6 yet.

If you can, get hold of your ISP and ask them whether IPv6 is fully supported on their network. Chances are probably not.

Hope that helps

I didnt have to disable IPv6, it was already disabled prior to following your instructions. I guess the network adapter just needed a reset. I assume with the computer restarting it would reset the network adapter but obviously I am incorrect in assuming that. Either way THANK YOU for your fix!

Top man and anytime