Dropping Ethernet Connection on Big Sur

@everyone:

I am convinced this is just a Wi-Fi side trouble ( "Wi-Fi 6" more accurately ). To workaround this until Apple fixes it,

I suggest to simply turn off Wi-Fi, check on https://www.nperf.com/

that your connection on Ethernet only is back on full speed.

Please, if you test this simple method ( which won't break anything, just the opposite ),

report here if it is successfull or failing.

@rappdw I would like you to test the following receipe:

• turn Wi-Fi off and keep it off,
• open System Preferences… > Network
  • which color is the big led before Ethernet?
  • if it is red, then
    • Make Service Inactive ( drop down gear menu )
    • Make Service Active
    • which color is the big led before Ethernet?
• close System Preferences… > Network

That is so bizarre - I followed the advice to adjust the energy settings. The moment I un-checked "Wake for network access," the wired Ethernet connection turned green again. This is connected via a Dell Thunderbolt dock (TB-19) with the Ethernet cable connected via the dock.

Thanks for the clue, Wangwang.

I'm having this same problem. Appears to have to do with com.apple.DriverKit.AppleUserECM.dext kernel driver extension. It just crashes randomly, but unsure as to cause. I thought it might be the ThinkPad USB-C dock I was using so ended up buying a Thunderbolt 3 dock from Anker. Same issue. The one thing I found in common w/ these two was the RealTek Ethernet. This particular adapter appears to have issues w/ Big Sur and was only circumvented on Catalina by installing RealTek's kernel driver extension that is not support by Big Sur.

So long story short, accessories sold by Apple are less likely to have this issue. I'd also argue that if accessories sold by Apple have an issue, it becomes an easier conversation w/ Apple to fix their driver. I'm picking up a CalDigit dock to see if this problem continues.

One, open a support request with Apple. Two, what kext name do you see for your Ethernet?

Apple Icon > About This Mac > System Report > Ethernet Cards

I was having particular issues w/ the com.apple.DriverKit.AppleUserECM.dext extension.

The caldigit ts3 dock I got uses the AppleIntelI210Ethernet.kext kernel extension and has been solid.

Follow up to my earlier post re VPN software compromising my connection.

After a very comprehensive removal of my VPN software, I was able to reinstall it and am using the internet, Ethernet and WiFi with no issues now.

I had same problem until yesterday and in my case it was UPnP from router. I turned it off and my Mac Mini M1 now runs fine. The router I use is UniFi Dream Machine (Base version, not Pro).

It was kinda hard to point out the culprit because my 12-inch Macbook which also runs Big Sur is completely fine with UPnP turned on.

So if UPnP is turned on, try turning it off. I hope this info helps.

Murphy5156 wrote:

[...] If I restart the iMac everything is fine until a few hours later when it will lose connection again for no reason. Any ideas?

If you are still blocked in your work by this Big Sur bug, next time, try the following quick workaround:

open a Terminal,

enter the following commands:

/usr/bin/sudo ifconfig en0 down
/usr/bin/sudo ifconfig en0 up

These two commands will perform an off/on of your Ethernet interface,

a kind of software unplug and then plug the Ethernet cable.

Advantage:

you won't play the game of planned obsolescence of RJ45 Ethernet connectors ( which are not really

strong to resist to an everyday back and forth game ).

Dear Luis,

I can change this in System Preferences -> Network -> Ethernet -> Options -> Hardware.

I change the settings to "Manually" and I can enter 1501 into the MTU field without a problem. I am on 11.5.2 but I assume that makes do difference. I still assume this might cause problems with some network applications, but so far it works without a problem for two weeks.

It's just pathetic that the basic Ethernet settings in the current macOS don't work anymore, even on the latest models and after many revisions of the system software. This is "Windows-level" software quality. It seems that there should be more competition. Apple doesn't seem to care much about software quality anymore. I've been using Apple for more than 20 years and have never seen such embarrassing bugs like this one in the basic Ethernet driver software and they seem to just don't care.

Regards

Stephan

I have what sounds like the same issue on a 2021 M1 mini. Both hard wired and wifi. I've had apps/chrome tabs just stop working while others keep running. Today for example Jira in Chrome wouldn't load at all. Same URL in Safari was fine. Terminal wouldn't quit or launch (after I force killed it), but mail was fine. I disabled the ethernet port in network settings and everything worked again on Wifi only. Turning ethernet back on, things still worked. Disabled wifi to be 100% ethernet and it was fine. So just the act of resetting the port (probably unplugging cable, disabling port, changing network settings, rebooting the computer etc) seems to reset whatever the software issue is.

This seems to be a new Big Sur issue. I'm on 11.6 and it started within the last couple of weeks.

Behavior with a bad port is terrible. Apple really needs to work on better I/O handling when it encounters a bad USB drive or flaky network port.

My suggestions for now:

• Go 100% wifi until Apple fixes it
• Toggle the hardwired port on/off when it goes flaky
• Don't upgrade to latest Big Sur

Dulcamara1p wrote:

I am having the same problem. Connection drops every 1--3 days since installing Big Sur 1.1. The drop only happens overnight.

Do you just sleep the computer overnight? If so try shutting down and reboot in the morning. That has the added benefit of clearing out temporary system and application cache and swap files which will help with performance.

Also give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

It is now 4 days later, and my network is still working. Rebooting alone did not fix it. The only thing I did was reset the SMC, as mentioned above. Google that, as it is different for different machines.

@mr_ggg:

could you enter the following command inside a Terminal window:

grep -C2 EEE /System/Library/Extensions/IONetworkingFamily.kext/Contents/PlugIns/AppleBCM5701Ethernet.kext/Contents/Info.plist

and bring us back the 5 lines of result?

Running Big Sur 11.2.3 on a 2017 MBPro. I have wasted weeks trying to get a stable internet connection with Big Sur. Drop outs all over the place and very, very slow and unreliable when it stayed connected. I spent fruitless hours downgrading to Catalina. Wiping disks all along the way and then upgrading back to 11.2.3 to no avail.

I have now been running cleanly, quickly and reliably for three days. I found the solution that works for me accidentally. Connect via WiFi only and DO NOT use Ethernet at the same time. Ethernet with no WiFi does not do it for me but WiFi with no Ethernet seems to be working OK now for three days and I've been hammering it .... catching up on weeks of lost time and productivity.

@mr_ggg,

I agree with you, the extra interfaces aren't the core of a problem,

but:

• they highly complexify the real problem analysis which is here on one Ethernet interface alone,
• they are fully normal on a Mac which is playing the role of a router or a firewall in a network,
• their growing number might be the signature of a real bug in software managment of interfaces upon switching

    one on/off/on.

@everyone,

if you want to help focus on this problem and help everyone, I suggest to make a specific configuration

with only the problematic Ethernet connection ( either USB or Thunderbolt, but not both in the same configuration ) activated and on.