Expert advice needed ASAP!: Can't get Ethernet setup with USB adaptor

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Level 1

79 points

Expert advice needed ASAP!: Can't get Ethernet setup with USB adaptor

I'm suddenly seeing a problem where my MacBook is refusing to connect to Ethernet, despite that a known working USB to Ethernet Adaptor (Realtek chip) is connected to the MacBook.

The adaptor I'm using is a standard USB to Gigabit Ethernet adaptor, using a Realtek chip. So no drivers are necessary, and has worked flawlessly in the past.

All of a sudden, it would not detect the Ethernet connection at all, even though the System Information clearly shows that the "USB 10/100/1000 LAN" is connected and working. Even if I connect a cable to the adaptor, it doesn't go online in the Network Preferences panel.

I thought I might need to delete the connection and add it again, only to find that you can't add the USB Ethernet connection in Network Preferences, as shown below.

Note how it is detecting the USB adaptor, but doesn't appear in Network Preferences.

I'm stumped. Any help appreciated!

I've posted a same question on the Big Sur forums, but with no help or reply whatsoever... perhaps the MacBook section may be better thus reposting the same question here.

Posted on Jan 7, 2022 7:05 AM

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Answer 1

Yoshihide K. Author

Level 1

79 points

Jan 8, 2022 4:49 PM in response to ku4hx

Have you tried a different adaptor? Not all devices are created equal. How about a different cable? Is your internet signal as strong as it should be? Is your equipment up to date? How old is it? There can be many solutions, it's just that some may require more extensive trouble shooting and experimenting with setup options and equipment.

Yes, I've tried and tested all those basic troubleshooting for over a month with no success and out of ideas.

Tried 3 adaptors (Two Realtek chips, and one ASIX chip base) with no success.. The two Realtek based adaptors have WORKED properly with the SAME MacBook for years - I'm didn't buy anything new off the shelf with no research to find out it doesn't work with my setup. These adaptors have worked flawlessly for over 5 years on the same MacBook.
It's highly unlikely these adaptors somehow broke down simultaneously and somehow became incompatible only with the MacBook. All three adaptors are known good. Have confirmed they work on a Windows PC (HP Elite/Windows 10), a different Mac (Mac mini 2018/Monterey, Mac mini 2010/High Sierra). The Realtek based ones work perfectly on an iPhone or iPad via the Lightning-to-USB adaptor too.
Tried different Cables and connecting it to different Ethernet Ports on the hub with no success.
Tried rebooting the FTTH optical fiber converter, the Router (Yamaha RTX810), the main Hubs (Allied Telesys CentreCom GS916M) with no success.
Even shut down the whole power to my house to reset anything that may be causing the problem with no success.
Have a high quality FTTH optical fiber internet connection with speeds up to 500Mbps. Not a 5G or satellite connection where 'signal strength' may be the issue.
The OS is always updated to the latest version. The current version is Big Sur 11.6.2. (Note the MacBook 2015 is NOT compatible with Monterey)
Have tried resetting the PRAM with no success.
Tried resetting the PMU with no success.
Tried Reinstalling Big Sur with no success.
Tried a Clean install of Big Sur on a different drive with no success
Booting in Safe Mode doesn't help
Creating a new User Account doesn't help.
Attempting to boot in Internet Recovery mode doesn't seem to work either. I get a spinning globe and will not continue unless I choose a WiFi connection, possibly because it isn't detecting the Ethernet adaptor(s). Though I can't recall whether Internet Recovery Mode works with an external USB Ethernet adaptor in the first place.

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Answer 2

Yoshihide K. Author

Level 1

79 points

Jan 8, 2022 1:13 AM in response to Yoshihide K.

After some more research, I've found a solution.

The "System Integrity Protection" is the culprit of this problem and simply disabling it solves the problem.

Disable System Integrity Protection by booting in Recovery Mode, opening Terminal and typing in

"csrutil disable" and "reboot"

https://developer.apple.com/documentation/security/disabling_and_enabling_system_integrity_protection

Next install the Reaktek Ethernet drivers (though normally this is not necessary, it's necessary in this case to restore the connection)

https://www.realtek.com/en/component/zoo/category/network-interface-controllers-10-100-1000m-gigabit-ethernet-usb-3-0-software

Now the USB 10/100/1000 Ethernet connection will appear in Network Preferences and start communicating automatically.

DO NOT turn "System Integrity Protection" back ON as suggested.

It will break it and you'll be unable to use the ethernet connection again.

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Answer 3

ku4hx

Level 7

23,586 points

Jan 9, 2022 4:40 AM in response to Yoshihide K.

How about your modem? And router assuming you have one? How old are they? Are they running the latest firmware? There is a reason something is not function properly; security is not one of those things any manufacturer worth his salt will recommend you abandon or approve doing so.

"(Note the MacBook 2015 is NOT compatible with Monterey)". A problem with this statement is many people often drop the "Pro" or "Air" part for whatever reason so we never really know exactly what "MacBook" refers to.

Some 2015 MacBook Pro/Airs are in fact compatible with Monterey: https://support.apple.com/en-us/HT212551. Obviously if you have an actual MacBook (no qualifier) you are correct.

Maybe it's time to get a more modern, safer, MacBook Pro or Air if you have a MacBook.

Something is amiss. Like the man said, you don't sink the ship just to clear clutter off the deck.

I'm dry and grasping at straws. All I'll add further is you need to keep security active. Whether you do so is up to you. It is, after all is said and done, your machine and you're free to use it any way you choose.

Good luck.

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Answer 4

Yoshihide K. Author

Level 1

79 points

Jan 8, 2022 4:38 AM in response to ku4hx

But unfortunately, this seems to be the only solution.

I’m open to better solutions, but nobody so far has, and this last resort is probably the only solution.

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Answer 5

ku4hx

Level 7

23,586 points

Jan 8, 2022 8:25 AM in response to Yoshihide K.

"But unfortunately, this seems to be the only solution."

Have you tried a different adaptor? Not all devices are created equal. How about a different cable? Is your internet signal as strong as it should be? Is your equipment up to date? How old is it? There can be many solutions, it's just that some may require more extensive trouble shooting and experimenting with setup options and equipment.

I've got five Macs: three iMacs (2020,2020,2015) and two MacBook Pros (2016, 2020). None have ever had to have any security disabled to be able to connect to the internet; all have used wireless and wired at one time or another. I'm just one person and one is a row is not a trend, but disabling SIP to get your system to work is a clue something is amiss.

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