Windows 10 Pro Link Speed Changing On Its Own

Hi DJFroid ,

specify whether it is a desktop PC or a laptop.

1) Is your computer connected directly to the router or via the ethernet socket on the wall or via a hub / switch?

2) What category of network cable are you using?

3) Did your computer previously run at 1 Gbps speed, or has this problem only appeared recently?

The network adapter must remain set to auto-negotiation, those settings must not be changed.

Thank you for your reply.

To answer your questions:

Specify whether it is a desktop PC or a laptop.

 - Intel NUC, Desktop PC

1) Is your computer connected directly to the router or via the Ethernet socket on the wall or via a hub / switch?

 - Connected via Ethernet cable from PC to a new gigabit switch. From there, the switch is going into a Ethernet wall socket. I set up the network myself, rewired an incorrectly made RJ45 connections, and tested with my Fluke network tester. All pin configurations and network speeds between the wall and the router are solid. I also have a Mac Mini on the same desk connected to the same switch and it connects at Giga speeds no problem. Have swapped Ethernet cables between the Mac Mini and the NUC PC and the Mac Mini always connects at Giga speeds. Troubleshooting has definitely isolated it to the PC only.

2) What category of network cable are you using?

 - Cat5e. As mentioned above, have tried multiple cables and get the same result, the eventual drop from Giga to Mega connection.

3) Did your computer previously run at 1 Gbps speed, or has this problem only appeared recently?

- It did previously run at Gbps and have a Gbps connection, as I was able to verify in the "Ethernet Status" window of the "Network Connections" screen via Control Panel. Speed will show connected at 1.0 Gbps, then the network icon will flicker and switch to the "no internet" globe, then the network icon comes back, and it is then reconnected at 100 Mbps speed.

The network adapter must remain set to auto-negotiation, those settings must not be changed.

- I did change that back as it was acting odd, but thank you for verifying this setting. I will leave it be.

Hope this additional information is helpful and thank you again for responding.

Hi DJFroid ,

in order to completely isolate the problem it is necessary to temporarily connect the Intel NUC directly to a LAN port of the router for a long enough time to check if the problem is solved or not in this mode. Also, temporarily disconnect any other devices from the Intel NUC.

Good morning @Franco

Thank you again for your continued help.

After about 24 hours of testing and troubleshooting, here is what has transpired:

- Plugged in NUC directly to router as suggested and the PC booted up into Gigabit connection

- Also realized I never disabled auto-tuning in the command shell, so adjusted that setting

- System ran and stayed connected at Giga speeds, although I did notice random disconnections and then re-connections from time to time. The was called to my attention with I was in Facebook and the popup window in the bottom left corner would randomly say "offline." After about 5 seconds, it would reconnect and reconnect at Gbps speeds, which it used to not do. So there seems to be a drop off...something...happening at random intervals.

- The very interesting discovery was when the computer went into sleep mode after being left idle for awhile. It would drop to Mbps speeds (noticed the light on my router [Netgear] switch from white to orange, denoting the change) and when I woke the computer back up, the connection stayed in Mbps speeds and would not return to Gbps; even when I disabled and then re-enabled the Ethernet connection in Control Panel.

- I'm currently running Windows 10 Pro, 1909, build 18363.1316.

- As I noticed these problems happening around the 29th or 30th of January (based on when I ordered my new switches), I'm wondering if this is a bug in Windows as the system took 3 various updates on January 13, and another Cumulative update on January 27.

From this point, I have also set a static IP on my NUC, changed my DNS to Cloudflare, and disabled the second Ethernet port on the system, all in an effort try and create some stability in the network connection.

I'm going to put my NUC back in my office and reconnect to the switch to see if it responds the same as it did when directly connected to the router, but I have a feeling it will.

Any more thoughts on how to stop the random disconnections would be greatly appreciated, or at this point, are we just waiting for another Windows 10 update and hope they have fix in the new version?

Hi DJFroid ,

try to change the Power Management options on the ethernet network card: go to Device Manager> network adapters, select your network adapter in use, click on the Power Management tab, uncheck the checkbox: Allow the computer to turn off the device to save energy. Click on the Advanced tab and disable any options concerning energy saving, such as Energy Efficient Ethernet (EEE), Green Ethernet etc.If you have the option, try using a CAT 6 network cable.

Good afternoon @Franco,

Your persistence is greatly appreciated...lol

I was aware of the Power Management "turn off device to save energy" option and had done that previously. However, I was not aware of the EEE setting and that was in fact enabled. I have turned that off and will monitor the connectivity and performance for another 24 hours. I will also look into a Cat6 cable, although after the EEE setting adjustment and restart, it seems to be holding a Gbps connection and I am getting a max return on my speedtest from my ISP.

Thank you again for all of your help and suggestions in diagnosing this issue and fingers crossed this will resolve the problem.

Hi DJFroid ,

ok, let me know how the situation evolves.

Good morning Franco,

Sadly, the situation persists. For whatever reason, the connection hung in solid for about half a day, then started disconnecting and reconnecting again. I have resorted to resetting the network in the Windows settings and see if that would work. It did not, and about 5 min into the restart, it disconnected and reconnected...same, from Gbps to Mbps speeds.

While I don't have a cat6 cable, I'm fairly sure that a cable won't make the difference at this point. The fact that the system will connect at boot up to Gbps speeds, then go offline and reconnect at Mbps speeds after about 5 seconds seriously leads me to believe this is either a Windows problem or Intel driver problem. Both Ethernet ports on my NUC Ghost Canyon are acting the exact same way, and I've finally resorted to disabling them both and just using Wifi. While the wifi connection is holding at between 400-500 Mbps, my current ISP package caps me at 260 Mbps anyway, so I'm not being restricted at the wifi. Even with the door to my office closed (Router in the hall at center of the house), I'm still getting 240 down and 108 up...so double what I get on my hardline when Windows decides to be temperamental.

I'm definitely open to still trying various options, but at this point I think I'm at the mercy of Microsoft making a patch or update that will correct this...or Intel?

Thank you and I look forward to any other thoughts you have.

Good afternoon Franco,

Thanks again for your continued support.

As suggested, I have bypassed the switch again and gone directly to the router. Regarding the computer, the items plugged in are:

- Mechanical Keyboard

- Kensington Trackball Mouse

- 3 computer monitors

- 1 USB Hub

- 1 USB to Lightening cable to keep my iphone charged

- 1 Ethernet cable

The link has been holding strong for about 30 minutes, so I will continue to monitor. I guess it wouldn't be outside the realm of possibility to think the switch was bad out of the box...stranger things have happened...lol. Also, I'll troubleshoot by ether adding or subtracting devices and monitoring the connection at each go around. Bluetooth and Wifi have also been disabled now.

It's good to know this is not a common or widespread problem across other windows users, so maybe cranky hardware is the place to refocus again.

Best,

Froid