Ethernet adapter not working with big sur update?

I have a suggestion for bishopcheen. I had the same problem with thunderbolt to ethernet on my 2014 Mac book pro and I tried several ways to fix the problem. Reset the SMC, reset the PRAM, delete the p file and restarting the mac and nothing worked. Asumming its not a hardware problem ( you can check with these steps https://support.apple.com/en-us/HT202731). I talked to apple support and we decided to to do a clean install Big Sur. https://support.apple.com/en-us/HT204904 Make sure you have a back up and an internet connection upon before restarting in macOS recovery mode.

i appreciate the suggestion OneEskimo but according to Apple Support and the long thread of this Big Sur compatibility discussion, there is not an Enternet adapter for a Macbook Air 2016 USB 3.0 port that is compatible with 643 bit OS 11.0 Big Sur. My USB 3.0 adapter from StarTech was very compatible with OS 10.15 Catalina (my current OS) but Star Tech has not developed the drivers for Big Sur for its Ethernet adapter. It was not very happy with Apple either for the lead time and support it was provided. So, a clean install of Big Sur will not likely work unless i reduce my ethernet down to about 92 Mbps with USB 2.0 Apple Ethernet adapter vs. about 236 Mbps with my StarTech USB 3.0 ethernet adapter.

I have the MacBook Air 2017 model.

I tracked this issue for a while over Xmas and New Year as I also had the same problem: I have a Ugreen USB 2 Ethernet Adaptor. After the Big Sur update, it stopped working.

Being a Mac novice I was very reticent to do the software changes as recommended in this post to counteract the Asix chipset issue, though I am sure they work great. So being a coward I read all the replies, and that had me visiting the Plugable website. Their USB 3/ USB-C Gb Ethernet Adaptor (code USB3-HUB3ME) seemed to be the one to go for as it uses the Realtek chipset, and not the problematic Asix stuff. And it means I can still use the Thunderbolt port for my HDMI monitor connection.

And today I took delivery of said Plugable adaptor. It has both USB 3 and USB-C leads. I used the USB 3 and it worked first time. So far no issues to report. Happy days at last.

Downside is the £25 cost. The Hub does include 3 USB ports though, as well as the Ethernet connector, so could pave useful for other things too.

Over.

It may be that the adapter needs a Driver update from the maker. Check the with company that made it.

For example I have a J5 ethernet adapter that the company states a warning on their main page that their device will not be compatible with latest update until further notice

Okay, a similar problem I had on an old iMac (Updated to Big Sur and ethernet quit working). I solved it by going to System Preferences, Network, Advanced, Hardware, and changed the MTU so that it matched the MTU of my network.

In my particular case I believe it is having trouble negotiating any difference. If you set it to a different MTU it may not work at all, or temporarily, or it may appear to work but corrupting data. I have images I transferred over the network that have artifacts (misplaced sequence of pixels in the images).

When I set to the exact MTU of our switches, everything worked perfectly.

Apple should not be taking this long to solve this. It seems they're too busy being involved in political matters.

Hi bishopeen 'I was in your train of thought regarding speeds in thunderbolt and i thought my my Belkin adapter was not compatible with Big Sur . Then I realized after researching a little I realized ports have a max speed and the actual speed is driven by what device you plug it into,. for example in your case the USB 3.0 (also known as SuperSpeed USB) has a maximum bandwidth rate of 5 gbps (gigabits per second. So if you plug it into a gigabyte it can do gigabyte and and if you plug it into 100 Mpbs it can do 100Mpbs. Thats when i realized may be it its not the adapter compatibility since they don't come with any software drivers when you buy them. I had two thunderbolt ports not working after updating to Big Sur and I started shopping for another adapter. Not one vender displayed specs regarding System compatibility, just hardware compatibility. Thats when i called Apple support. They were convinced that I had a hardware issue after trying a few things like SMC , PRAM etc. They were already setting me up to send my computer in for repair. Then i said how does two separate ports go at the same time and I really believe this happened on my OS update to Big Sur. Then i was asked if I have the time to do a hardware test and it passed and then we did a clean install of Big Sur. Believe me i was and the support tech who was very helpful was shocked it worked. I have no ill will toward Apple and their tech support is not perfect but as long as i was patient we found a solution. I did look online or other brands of adapters for your application and found this one QGeeM USB Ethernet Adapter,USB 3.0 to 10/100/1000 Gigabit Ethernet LAN Network Adapter Compatible for MacBook Air/Pro,Surface Pro,iMac,Vista,Notebook PC with Windows7/8/10, XP.

if you are not comfortable with doing a clean install, apple chat support will walk you through it... they are there to help.

I have a Macbook pro with a baseus ethernet/USB adapter (the ethernet component is Realtek).

It was not working properly after Big Sur last update.

I found a driver update for MacOs on Realtek website and now it is working.

Ivan, thank you for the post. Basses makes a lot of adapters. which one do you have?

Is it USB 3.0 which allows for much faster speeds of 230+ Mbps vs USB 2.0 at 90+ Mbps? The reason i ask is the Apple USB 2.0 Ethernet adapter will work with Big Sur -- I have that adapter -- but the speed will be slower than i want/need/desire and currently have with my USB 3.0 StarTech adapter.

Star Tech does not know when it will have a compatible Big Sur driver available and is not very happy with Apple's communication about Big Sur to peripheral makers.

Again, i appreciate what you told me already, but if you have more info about the speed and the specific adapter, that would be very helpful. thanks Ivan

I don't know if this would help anybody because I was on an iMac... but the symptoms were the same.

I went in to System Preferences » Network » Ethernet » Advanced... » Hardware »

and set

Configure: Manually

Speed: 1000baseT

Duplex: full-duplex

MTU: Jumbo (9000)

"deselect" AVB/EAV Mode

OK

Apply

and try it.

I had similar issues on a OMC Thunderbolt 4 hub - this has the Realtek ethernet chipset in. Attaching a thunderbolt to ethernet dongle worked.

I installed their USB-C dock ethernet drivers - found here https://www.owcdigital.com/support/software-drivers and the hub ethernet port is now operating correctly

Here a MacBook Air 2017, after updating to macOS Big Sur yesterday, no Ethernet network.

With an Apple Thunderbolt - to - Gigabit Ethernet - adapter there is now a Ethernet network.

Thunderbolt-naar-Gigabit Ethernet-adapter - Apple (NL)

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.

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.

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