Ethernet adapter not working with big sur update?

We have more than 20 iMacs 27-inch, 2017 in our company. All have the same problem with Ethernet not working anymore after the Big Sur upgrade. We had to downgrade all Macs to Catalina again and everything works fine. It took many days of unnecessary work to do all this. Thank you Apple! This is Windows style. We waited until 11.2.1 to upgrade and were sure the basic bugs have been removed since 11.0.

The strange thing is, that most of the iMacs Ethernet ports all worked for ONE working day after the Big Sur upgrade. The next day the Ethernet ports were all not working anymore. How can this happen?

Another strange thing happened, when I used a new M1 MacBook Pro with an Ethernet adapter to connect to our 4D Server. It worked, but the Ethernet connection produces reproducible errors in connection to 4D Server. I tried 4 different USB-C to Ethernet adapters. It could be reproduced with all of them. Using WiFi, this problem did not occur. It really seems that Apple has broken the Ethernet drivers in Big Sur.

This is a severe problem, because many companies are using Ethernet connections. Obviously Apple does not care about this problem yet or isn't even aware of it.

Apple, if we can help to solve this problem let us know. But please start to work on it. This is getting a problem and we will not be able to upgrade to Big Sur because Ethernet is really required in companies.

Since Big Sur hasn’t been released yet (will be tomorrow), you’re using the beta version and you’re basically on your own. Install the full release tomorrow and see if that corrects the issue.

This may sounds weird, but after i plugged it into my ipad (worked) and then into my macbook pro it did work with that as well. Had the exact same problem and was able to solve it this way.

after doing EVERYTHING on my end to diagnostic the problem. I believe this is definitely a firmware problem. Since they can’t release firmware update like they did with the OS, without swapping out the hardware, I don’t think it can be fixed in the short run.

Just got response from apple, they want me to change the I/O board. Luckily I still have apple care since the logic board on the iMac Pro cost a fortune.

I found a way to use my adapter and more info about how it happens.

How to use

My adapter works only when I close the lid and use my external monitor, by the way adapter doesn't work immediately and I need to bring it down and up one or multiple time by this command:

sudo ifconfig en7 down; sudo ifconfig en7 up

How it happens

As I mentioned above my adapter disconnects when I open the lid. When my lid is closed I am connected for hours (top to 8 hours according my VPN timer), but when I open the lid after few minutes I cannot send packed. I say cannot send because I am in video chat (the very reason I open the lid) and when it happens I am still receiving other data but they don't.

I hope above description helps Apple support and technical team to solve the issue we encounter.

Dear OneEskimo,

thank you for your reply!

We use 4D client and server version 18.4, which they released for full compatibility with Big Sur and the M1 processor. Of course, we wouldn't have even tried to upgrade to Big Sur on any machine without being 100% sure that our most important software is 100% compatible. Your 4D link is related to version 15, which is many years old.

The only non-Apple software on all our iMacs is 4D. That's why we always make a clean install from scratch if there is a significant system update and then, we copy the 4d client after the machines work correctly. None of the iMac's Ethernet ports worked after the clean install. The driver must be broken since Big Sur because this was a clean install on ALL machines.

The problem with the M1 MacBook Pro is a different one. It is just another hint that the Ethernet driver of Big Sur is broken, as there are errors via the Ethernet connection and the WLAN connection works correctly.

Of course, you are right that we should have tried this on only one machine first. And this is what we did. It worked on the day of installation. The next day, the Ethernet did not work anymore. Nothing was installed or changed. That was spooky, but the same behavior and problem on all 2017 iMacs. The driver in Big Sur seems incompatible with the Ethernet chip Apple used in the 2017 iMacs.

Thank you for your answer again!

Regards

Steffel

A few people have recommended adaptors earlier in this thread. I bought a Plugable one and it worked a treat.

worked like a charm! After reboot, in System>network the Apple USB-ethernet adapter appeared in the list

MacOS11.3 enabled my belkin USB Multimedia Adapter(Model:AVC005btBK-A) to connect to the Internet.

The same for me, I upgraded to MacOS 11.3 and my Ethernet adapter works after without any issue. Hooray!

I purchased a Belkin multimedia Hub after upgrading from Catalina to Big Sur, because the other adapter I had would not work. This Belkin multimedia Hub works for USB so far, but with the ethernet, it sometimes suddenly disconnects. I had an Apple USB-ethernet adapter, so I tried plugging that into the Belkin adapter, and for whatever reason, that has worked for me so far.

So, it is MacBook Pro--Belkin--Apple USB-ethernet adapter --Ethernet cable

The Belkin is: https://www.amazon.com/Belkin-1-MultiPort-Adapter-Pass-Through-Charging-Ethernet/dp/B08PXVLQPM/ref=sr_1_4?crid=Q21UG4BOBZ2&dchild=1&keywords=belkin+usb-c+to+ethernet+adapter&qid=1614098185&sprefix=belkin+usb-c%2Caps%2C310&sr=8-4

The USB-Ethernet adapter is:

https://www.amazon.com/Apple-MC704LL-A-Ethernet-Adapter/dp/B00W7W9FK0/ref=sr_1_3?crid=2EO0JPLVLN6I9&dchild=1&keywords=apple+usb+ethernet+adapter&qid=1614098398&sprefix=apple+usb+et%2Caps%2C304&sr=8-3

There are others in this thread who have simpler solutions, I think. But I hope you find something that works.

made by who? Belkin? model number? sorry to ask more specific questions but Belkin makes many ethernet adapters and most are not compatible with Big Sur. Thank you for your valuable time time.

I've bought one of the Plugable adaptors mentioned in the link and it worked immediately! Great recommendation, thanks!!! I went for the cheaper option in case it didn't work, so cost me £15.

first of all my computer is fixed. interesting fact is my Big Sur build is 20B50 rather than 20B29 like everyone else. I got this by enabling ip range 17.0.0.0-17.0.0.8 and install from internet recovery.

If your firewall supports using hostnames, you may be able to use most Apple services above by allowing outbound connections to *.apple.com. If your firewall can only be configured with IP addresses, allow outbound connections to 17.0.0.0/8. The entire 17.0.0.0/8 address block is assigned to Apple.

Hope this helps.

I'm on a M1 MacBook Air and my ethernet connection through a AUKEY USB C Hub 8 in 1 Adapter was dropping constantly.

After several failed attempts to reconfigure my network settings, I tried your suggestion and connected the charger cable to the hub and it has been working flawlesly since.

I guess some hubs need more power than a Macbook Air can deliver.