After struggling with this same issue with a new iMac, we found a working and hopefully permanent solution.

Our set-up consists of a new 2020 iMac 5K, connected to a fast network and storage with 10GB native Ethernet (Custom order iMac) and for the connection to our Nexis we got 2 x USB 3.0 Ethernet adapters, TP-Link UE300 gigabit for aggregation.

We found that our adapters use a Realtek 8153 chip which is very common for these type of adapters, but this method should also work with other chips that have drivers available for MacOS Catalina.

So, the issue is that Catalina uses generic Apple drivers for USB Networking which are not compatible with Nexis software, which depends on the driver to report link speed and duplex. And the operating systems does everything it can to use its drivers instead of third party ones, even if they are present (installed) in the system.

So here’s what we did, step by step, all the commands should be typed without quotes:

• boot into Recovery Mode by pressing Command+R before OS start-up
• After it boots, go to the top menu and open Utilities then Terminal
• input the following command in the Terminal (no quotes): “csrutil disable” and press Enter. This will disable Sistem Integrity Protection which is needed to do the following operations. Don’t worry we will re-enable it afterwards.
• type “reboot” and press enter, then holding Command+R again to return to Recovery mode
• again go to Utilities then Terminal, and type “csrutil status” it should say it’s disabled

In the Terminal type the following commands and press Enter after each one:

• “mount -rw /“ this will mount the storage with read-write privileges

For the following commands, replace “Macintosh\ HD” with whatever name your primary drive has:

   -  “cd /Volumes/Macintosh\ HD/System/Library/DriverExtensions/“ this will take you to that folder on your primary storage (it won’t show up in Terminal)

Then

   -  “rm -rf AppleUserECM.dext”

Then

   -  “rm -rf AppleUserECMData.dext”

This will delete Apple’s driver extensions we want to get rid of.

Now let’s go back to root and then to the drivers folder

   -  “cd /“

   -  “cd /Volumes/Macintosh\ HD/System/Library/Extensions/“

Now let’s delete the drivers Apple OS insists on loading for these USB Ethernet:

   -  “rm -rf AppleUSBECM.kext”

   -  “rm -rf AppleUSBNCM.kext”

   -  “rm -rf AppleUSBNetworking.kext”

   -  “reboot”

Let it reboot in normal mode. Now hopefully you have the driver installer for your USB Ethernet. Generic ones from Realtek work for most of these cards it doesn’t matter if it is TP-Link or Belkin or others, the patcher included in the installer has many vendor and product ID’s built-in. I don’t know if I’m allowed to post external links but it should be easy to find on Realtek or manufacturer’s website.

The installer from Realtek will request a restart after installation, if your does not do restart the system after install.

Now your connection should work, just put your IP’s and Avid Manager now will mount the Nexis storage and it actually works very, very well.

After you make sure everything works as it should, reboot again in Recovery Mode, open Terminal and type “csrutil enable” then “reboot” to re-enable System Integrity Protection.

That’s it, as usual with problems like these the hardest part is to figure what is the cause, what options there are for a fix and testing those options.

We are testing since last month and everything works great now.

Thank you for this guide d3xmeister.

This solution works great so far on two new Mac Pro 2019 using cheap adapters with the Realtek chipset.
Two adapters per computer get around 160 MB/s R/W on ISIS 5000 which is more than enough for the current workflow.

If it looks intimidating to anyone I can assure you it is a lot easier than it looks.

I am running Catalina as well and cannot connect to the NEXIS Client Manager v. 21.3.0.21. I can ping the server which is an ISIS. I am using the Belkin USB C to Ethernet adapter F2CU040 and it appears to not be compatible according to this thread and the Avid README notes.

Will the Apple Thunderbolt to Gigabit Ethernet Adapter work with Catalina and the ISIS Client Manager instead?

Running on MacBook Pro 2018 Retina 15".

Yes, see page 26 of the readme:

(The following issue has been observed and is under investigation by Avid & Apple) USB-C to
1Gb RJ45 Ethernet adapters cannot be used to connect using the Avid NEXIS Client because
macOS 10.15 (Catalina) and higher reports the interface speed as zero Mbps.

Workaround: Use Thunderbolt 3-to-Thunderbolt 2 and Thunderbolt 2-to-1Gb Ethernet
adapters. Thunderbolt 3 to 10Gbps and 40Gbps adapters are supported with macOS 10.15 and
higher with the Avid NEXIS Client.

Alex Veloz:

I am running Catalina as well and cannot connect to the NEXIS Client Manager v. 21.3.0.21. I can ping the server which is an ISIS. I am using the Belkin USB C to Ethernet adapter F2CU040 and it appears to not be compatible according to this thread and the Avid README notes.

Will the Apple Thunderbolt to Gigabit Ethernet Adapter work with Catalina and the ISIS Client Manager instead?

Running on MacBook Pro 2018 Retina 15".

Hi Alex, your adapter will work. Follow my tutorial above, and after you complete all the steps, just google "realtek rtl8153 driver" and download the MacOS driver package from offical Realtek drivers website. It's the version 1.0.22 from 10.9-10.15. After you install that, everything will work. I've done exactly this just last week, with dual USB adapters, and it works flawlessly.

Thank you Bob and d3xmeister. The turorial worked and I am now able to use the Workspaces.

I ran into a little problem with changing directories and kept getting a "volumes does not exist" error but figured it out and proceeded.

Thanks again.

Hi
Do you have the same procedure for macOS Monterey?

I don't think it will work, we did not upgrade. I don't think Media Composer works on Moneterey at all

Media Composer for Monterey and M1 based Macs was released yesterday:)

That was fast, usually it takes at least a year and that's not even for major releases that change core technologies in the OS.

Support for newer OSses is fine but not needed here - we tend to use matured / proven OS versions!

Keep in mind, that with macOS versions higher than Catalina dongles will not work! 

Keep in mind that MacOS older than Catalina no longer receives security updates from Apple, for those of us in remote workflow situations where airgapping isn't an option, support for modern operating systems may be a requirement of our network contracts.