Ethernet adapter not working with big sur update?

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 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.

Bit late reply but I found this as an answer to this problem another website:

"Official release big Sur 11.0.1

Anker USB-C to ethernet works

Tripp-lite USB-3 to ethernet DOES NOT work."

So I assume USB 2.0/3.0 don't work on this iOS anymore, which sucks because I'm in the same boat as you.

Hope this helped a bit

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.

Hey Duane Deal,

this works with my iMac! It is not a solution but a workaround, because some users will need AVB and some network clients are not compatible with Jumbo frames.

I spent days researching for a solution. This definitely was one.

Apple, why don't you check all the basic functions like the built in Ethernet hardware before you release a new system? This one is already version 11.2 and not 11 alpha or beta! Apple becomes more and more like Windows regarding the software quality. Please correct this incompatibility issue with your own hardware chip Broadcom 57766-A1 that you use in the iMac. Some people will need AVB and some can't use Jumbo frames in their environment.

I’ve had this problem both before and after Big Sur as well as with 2017 macbook and 2020 MacBook Pro.

Works for about 20 minutes and then freezes. Don’t know if single adapter vs hub type adapter will solve problem. That will mean 4 adapters, one for each USB-C port.

Im having the same problem on my j5create JUD380, USB 3 to Gigabit Ethernet on my 2017 MacBook Air. I’d rather Apple fix this problem so I don’t need to throw another $80 at equipment in the future for the same equipment I have right now.

I think it would be a good idea for Apple to comment directly on this and let us know when their hardware will work again with their software (Big Sur).

We all do not have ancient computers and they were all built by Apple. It is actually the least BEFORE the release of a new system software to make sure the existing own hardware works with it, so that such rudimentary functions such as Ethernet in a 2019 iMac are safely guaranteed to work by 100% in the beginning of 2021.

I have more than twenty Macs in my company and I cannot update them to Big Sur, because they all have the same Ethernet hardware. We are not in beta anymore and the version is not 11.0 but 11.2.1 already.

So Apple, when will you solve this big problem?

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.

MadokaO - interesting. I tried that adapter and it did not work with my MacBook 2019 or 2014.

I have not tried it with the ethernet on a separate adapter. I might try that.

I've had to get a powered hub - Belkin Thunderbolt 3 Hub.

https://www.amazon.ca/Belkin-Thunderbolt-3-Dock-Pro/dp/B07YLMJZXB/ref=asc_df_B07YLMJZXB/?tag=googleshopc0c-20&linkCode=df0&hvadid=361203164760&hvpos=&hvnetw=g&hvrand=1410244564722968926&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9001016&hvtargid=pla-841066038854&psc=1

I still have some disconnection/freezing with the ethernet cable plugged into this one, but the other devices (usb microphone, usb cameras, headphones, audio interface, iPad) seem to be working better. I'll try the separate ethernet cable with it. Seems a shame to have to spend close to 600 extra to make a very expensive MacBook Pro work properly and have a reliable wired connection. The whole point of ethernet/wired is for more stable connection. Sigh.

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.

If anyone has an option for USB 3.0 Ethernet connection to a USB port, please let me know. I cannot find an Ethernet adapter for USB 3.0 compatible with Apple OS Big Sur 11.0. i know that the thunderbolt Ethernet Gig adapter works fine for Big Sur --- BUT -- my Macbook Air 2017 has only one Thunderbolt port which i use to run my external monitor.

By releasing Big Sur without a USB 3.0 ethernet adapter compatible with Big Sur, Apple has made my 2017 Macbook Air nearly obsolete. that used to be a Microsoft move which drove a lot of frustrated Windows users to Apple. Now Apple is doing the same user unfriendly moves and we have no options.

what is your download speed with your Belken Hub and Apple USB 2.0 Ethernet adapter? I believe it would be only about 92 Mbps instead of a higher speed of about 236 Mbps with a USB 3.0 Ethernet adapter. Apple does not make a USB 3.0 adapter and other providers of Ethernet USB 3.0 adapters are not compatible with Apple OS Big Sur 11.0.