UNSOLVED
OptiPlex 3040 - No Ethernet on normal boot
Hi everyone,
I am experiencing a very strange Ethernet issue with my OptiPlex 3040.
When I boot the PC normally, Windows shows that there is no network connection, even though the Ethernet cable is securely plugged in. However, if I restart the PC, enter the BIOS screen (even just for a second without changing any settings), and then exit/boot into Windows, the Ethernet immediately starts working perfectly.
Here is what I have already tried to fix this:
- Installed and updated to the latest network drivers.
- Went into Device Manager and unchecked the option "Allow the computer to turn off this device to save power" under the Power Management tab for the network adapter.
- Tried different Ethernet cables and router ports.
It feels like a weird power state or initialization bug during a cold boot, but I am stuck. Has anyone encountered this specific issue on an OptiPlex before? Any advice on BIOS network settings or Windows settings to change would be highly appreciated.
Thank you!
6
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Posted September 11th, 2026 01:40
In BIOS, disable on-board Ethernet. Save it. Reboot and run computer. Reboot back to BIOS and en-enable and Save. I've see that fix weird-stuff (like NIC acting dead) a couple of times now.
If that doesn't work, sometimes it's just a bad NIC or Cable (both are cheap to replace).
In Windows, you might try "locking it" at 100 or 1000 (to stop the auto-negotiation).
(edited)
Dell Rockstar
Microsoft Windows and Apple iOS Developer (Retired)
- Like many of you, I can appreciate a good game-engine.
- I answer questions here, but I'm not a Dell employee.
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Posted September 11th, 2026 01:52
In my experience all these binary switches have some counter interference program button hidden somewhere in the matrix, so when you think you can enable or disable it, the system just does not behave in the way you think.
what I mean it there are multiple switches that can do the same thing, shutting off one does not do the job, but you would not know where all the switches are unless you were the master architect of Windows like the matrix God.
OP, a normal 3040 should not do that. instead of experimenting with all possible switches, try these common steps:
replace cmos battery with a new one
clear cmos settings using motherboard CLR CMOS jumper
delete all partitions on boot ssd/hdd and do a clean WIndows install
the three steps above attempt to start your pc from a clean slate and maximize chance of resolving issue.
5
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Posted September 11th, 2026 10:32
@redxps630 Hey there, i did a clean Windows 10 install and it worked perfectly until i installed the Realtek GBe Family Controller from their official website
(edited)
5
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Posted September 11th, 2026 10:33
@anne_droid What do you understand by a "normal boot"?
4
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Posted September 11th, 2026 10:44
Hi
I was trying to understand your remark "When I boot the PC normally".
I dual boot Linux Mint and W11, so sometimes it is a boot from POWER OFF state, and other times jusy a 'reboot' and select the Option from the screen.
However that all seems irrelevant as you have pinned down the problem to the "Realtek GBe Family Controller" driver.
Kind Regards
anne_droid
5
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Posted September 11th, 2026 10:57
@anne_droid I deleted the driver with a program called Revo Uninstaller, installed the proper driver from SupportAssist and thats all it still doesnt work
3
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Posted September 11th, 2026 11:10
Understood.
I dont have a direct ethernet port on this laptop, so sensible answers are not likely to appear here.
But I will give it some more thought.
Kind Regards
anne_droid
2
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Posted September 11th, 2026 11:29
Hi
Just for a comparison...
Open Command Prompt or PowerShell as Administrator, then run:
bcdedit /set {current} safeboot network shutdown /r /t 0Windows will boot into Safe Mode with Networking on the next restart. The
networkoption selects Safe Mode with networking rather than ordinary Safe Mode.Return to normal Windows
Because the command makes Safe Mode persistent, run this from an elevated Command Prompt while in Safe Mode:
bcdedit /deletevalue {current} safeboot shutdown /r /t 0So if it is then a cold boot you can test the port.
NB:
Low level connectivity may still be possible, a ping is pretty basic and well worth the effort...
ping 127.0.0.1
ping 13.107.4.52
PowerShell -Command "Test-NetConnection"Powershell Get-NetConnectionProfile
Kind Regards
anne_droid
5
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Posted September 14th, 2026 16:16
@justluka ,
I deleted the driver with a program called Revo Uninstaller, installed the proper driver from SupportAssist and thats all it still doesnt work
Try this ... completely remove as you are doing. Reboot and let it PnP.
Instead of Dell or Realtek.com driver ... just use the offered Windows-Update driver.
Since you are trying to fix wired-Ethernet, you might have to Temporarily use WiFi to get it (then switch over after new driver installs).
(edited)
Dell Rockstar
Microsoft Windows and Apple iOS Developer (Retired)
- Like many of you, I can appreciate a good game-engine.
- I answer questions here, but I'm not a Dell employee.
- Consider giving posts you like a "thumbs-up"
- Posting models-numbers and software versions speeds trouble-shooting.
- Click "Mark as Accepted Answer" on any post that answers your question best.
anne_droid
6 Operator
•
2287 Posts
•
8450 Points
6
0
Posted September 10th, 2026 20:52
Hi
Define 'Cold boot' and 'Normally' please.
Try a "Safe Mode" boot for comparison.
Is the IP fixed or dished out by DHCP every time.
Lots more details please.
Kind Regards
anne_droid