Problems with Ethernet Catalina 10.15.6

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Problems with Ethernet Catalina 10.15.6

MacMini 2018 (Catalina 10.15.6)

I have been having problems recently, my ethernet stopped working.

First it only stated self assigned IP, after I rebooted the router, changed the ethernet cable, restarted the mac and tried resetting all network settings (preferences, etc.) it seemed to work again for a couple of days.

Now it does connect to the router (IP assigned and everything) but no internet. I changed to another router, same thing. Cable connection and IP good, but no internet.

If I change under Ethernet Settings>Hardware, to Manually and Speed 10baseT/UTP everything comes back to normal (internet working fine), but soon as I change the speed to 100baseTX or Automatic Configuration, internet drops even when ethernet interface status is green (cable connection OK, IP assigned OK), simply no internet. It cannot be the router, because I connected another Mac through ethernet and working just fine at full speed.

Anyone with same issue?

Mac mini, macOS 10.15

Posted on Aug 8, 2020 12:23 AM

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Answer 1

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arturovall Author

Level 1

8 points

Aug 10, 2020 8:03 AM in response to Luis Sequeira1

Just to let you know that I proceeded with the following to isolate and resolve the issue:

1) Tried with 4 different ethernet cables, same problem. Connection green, but no internet. So the cable was not the issue.

2) Restore OS Catalina, did not resolved the issue.

3) Installed an older OS (Mojave latest App Store download) on a separate drive, have only ethernet on, everything came back to work. Connection and internet at full speed. This concluded that Catalina was the issue and not the hardware or cable or router. This is what led me to do the next step.

4) Clean reinstallation of Catalina. This solved my problem. Everything is working with ethernet.

Do not know the root cause exactly, maybe a faulty driver installation. Catalina was previously upgrade from Mojave, and every update since then automatically installed. Proceeding with a clean reinstallation is what resolved my ethernet speed issue.

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Answer 2

arturovall Author

Level 1

8 points

Aug 8, 2020 4:39 PM in response to Luis Sequeira1

Hi!

The DNS settings are being received automatically.

Yes I see the grey IP address and default DNS from my ISP. I added the 8.8.8.8 address as you specified but the internet is still down.

As mentioned in my previous message, the strange thing is that if I select a manually speed in the Hardware section to 10baseT/UTP the internet works. But it limits my speed to 10-Mbps Ethernet.

If I revert it to automatically or 100baseTX is where my internet drops. Still there is a green dot on my connection between Mac and router.

Is it hardware related or a ethernet device driver in Mac mini maybe?

Wifi does work fine.

This problem began to appear after automatic update to Catalina 10.15.6

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Answer 3

Aug 8, 2020 2:50 AM in response to arturovall

What are your DNS settings?

If there is a green dot then the connection between your mac and router is ok.

Click Advanced... then DNS.

Do you see a grey IP address? That is the DNS server your router offers by default (presumably from your ISP).

Try adding the address 8.8.8.8

and click apply. Any changes?

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Answer 4

Aug 9, 2020 12:53 AM in response to arturovall

It may be, as you say, driver issue, but I don’t think that is very likely, because that would surely affect a lot of people.

And this brings to what should have been on of the first things to try: the cable. Sometimes coincidences do happen. A bad cable might explain the failure to connect. And it may coincidentally have failed at or around the time of the update.

There is a way to prove and also a way to dismiss the idea that the cable is the problem. The first is easy. Try a new cable. The second is to install an older OS on a separate drive and have Ethernet working using the same cable.

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Answer 5

Aug 10, 2020 8:54 AM in response to arturovall

Great!

A clean install often fixes stuff. Many of the issues people find after upgrading result from something installed from before the update that did not work in Catalina anymore.

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Problems with Ethernet Catalina 10.15.6

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