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FWhite3 Author

Level 1

13 points

New Macs will not recognize ethernet

OK, so I'm at my wits end here. Last month I purchased three brand new macs to upgrade the computers in my house - a mac mini for the kids, a mac mini (with upgraded 10gb ethernet card) for my office, and an iMac for the wife. My house is wired for ethernet.

Here's the problem - NONE of the three new macs will recognize when I plug in an ethernet cable. I can only connect to the internet over wifi (which works, most of the time, but for speed and security reasons, I need ethernet to work).

I don't think it's a problem with the modem, or the router, or the ethernet wired through the house, or the cable I'm using - I know this because I have an ancient 2012 model Macbook with an ethernet port, and I can plug that in wherever I want and it sees the ethernet right away. I'm instantly online and good to go. BUT - when I take the same cable and connect it to ANY of the new 3 new macs, NONE of them recognize that I've plugged a cable in.

I've tried booting in Safe Mode - doesn't matter. Still don't see the ethernet cable. I've explored the "Incompatible Kernel Extension Configuration" bug that was reported back in 2016, but that's not it (I don't have version 3.28.1). I've confirmed that all three macs do, in fact, have ethernet cards installed (via "About this Mac" --> "System Report"). I've tried removing the Ethernet connection from the list of options on the Network window of System Preferences, with no change. I'm literally so frustrated here, and kind of think it has to be either something with my router/modem that just doesn't talk to newer macs, or something about Mojave - because it's just too weird that all three macs, all brand new, and all with different hardware configurations, would have the same problem.

Please help!

Mac mini 2018 or later

Posted on Sep 22, 2019 6:35 PM

Top-ranking reply

den.thed

Level 10

82,720 points

Posted on Sep 22, 2019 7:42 PM

Apple > System Preferences > Network > highlight Ethernet in the sidebar > click the Advanced... button > in the TCP/IP tab, click Renew DHCP Lease > then click OK.

It also might help, if you turn off Wi-Fi and move Ethernet to the top of the Service Order List.

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41 replies

FWhite3 Author

Level 1

13 points

Sep 23, 2019 7:07 AM in response to John Lockwood

Interesting. A couple of points of clarification:

1) Only one of the Mac Minis was configured with the upgraded 10Gb Ethernet support option; the other Mac Mini is the base configuration model, as well as the iMac that I bought (I bought all at the same time). I'm seeing the same issue of not recognizing the Ethernet from all three macs. The reason that I wanted to upgrade the one Mac Mini to 10Gb Ethernet was because I thought I was "future-proofing" it, but in retrospect that was probably stupid. :/

2) My other equipment:

Router: Araknis Networks 310-Series Dual-WAN Gigabit VPN Router

Switch: Araknis Networks 310 Series L2 Managed Gigabit Switch w/ 48 + 4 Front Ports

3) My wife has the Macbook and I'm out of the house all day - will need to wait until tomorrow to check the speed on the Macbook as requested.

Thanks again for the attempts to help me.

Sep 23, 2019 7:27 AM in response to FWhite3

Even with just the names of your network devices it is clear they should be 1Gbps capable which means they should work at 1Gbps on both a standard Mac mini and a 10Gbps capable Mac mini. By the way I was implying that they may have accidentally supplied you all three as 10Gbps models.

If a device is only capable of 100Mbps then it will only negotiate at that speed, 100Mbps can get away with using just four wires that is two pairs and can also get away with ancient Cat3 cabling. 1Gbps needs all eight wires i.e. all four pairs and at least Cat5 cabling. 10Gbps needs at least Cat5e, all 8 wires and can only run shorter distances. If your cable is only good enough for 100Mbps and the MacBook was so old it only does 100Mbps (unlikely) then this might account for the difference - hence the desire to check what speed the MacBook is using.

I have seen a case where a device (a printer) was 1Gbps capable, the network switch was 1Gbps capable but part of the cabling between them was ancient Cat3 and only 100Mbps capable. This resulted in the printer and the switch repeatedly trying to connect at 1Gbps and failing. In that case I initially 'fixed' the problem by manually configuring the printer to only connect at 100Mbps and later replaced all the old Cat3 cables with Cat5e ones. (It was the cables in the wall rather than the patch leads so this was a big job.)

Tesserax

Level 10

152,530 points

Sep 23, 2019 8:40 AM in response to FWhite3

Since you are using a managed switch, per chance did you apply any specific rules to the switch ports that these minis are connected to? ... or employed VLANs to them? hcsitas' suggestion to connect any of these minis temporarily to your Araknis router would certainly verify if there are any switch misconfigurations.

FWhite3 Author

Level 1

13 points

Sep 24, 2019 7:07 AM in response to Tesserax

Updated...

This morning I hauled up one of the Mac Minis upstairs, where the modem, router, and switch are. I tried plugging the Mini into all three devices, directly - none of them worked. Both the router and the switch have LEDs at the ports that flash in conjunction with activity across the cables plugged into those ports - at no time did any of the ports to which I plugged in the Mini light up. I confirmed that I was plugging the cable into working ports (by disconnecting a cable that was currently being used for another purpose), and when I plugged in the Mini - nothing. I tried with multiple cables, too. It would seem based on that experiment that this is not a modem, router, or switch problem, right?

Everything about this seems to suggest an issue with the Ethernet port on the Mini - and yet, is it not weird that I have three brand new macs, all slightly different in configuration, that show the same problem? Does that point more to an OS issue, or some setting somewhere that I'm not thinking of?

Sep 24, 2019 7:21 AM in response to FWhite3

I still have a suspicion all may have (incorrectly) been configured as 10Gbps models and this may be related to your problem.

If you are near to an Apple Store I would book an appointment with the Genius Bar.

Sep 24, 2019 1:23 PM in response to FWhite3

I would not get your hopes up.

The en0 interface is showing as inactive because it has not detected and made a connection. As an example I am typing this on an older MacBook Pro which has a built-in Ethernet port on en0 and WiFi on en1. As my laptop is only connected via WiFi only en1 is active and en0 is inactive.

It would be worth trying

ifconfig -m en0

This will display the capabilities of the en0 interface and confirm whether it is a 10Gbps version.

hcsitas

Level 6

12,986 points

Sep 24, 2019 1:40 PM in response to FWhite3

WYSIWYG: the mini doesn’t like the cable. Try a brand new 3 feet Cat 6a shielded cable to connect the mini directly behind router. If it works you’ll have baffling unanswered questions but none will matter. If it doesn’t, you’ll be out <$10. Good luck.

Sep 24, 2019 2:53 PM in response to FWhite3

That is weird, it seems to be detecting 1Gbps but not going active.

You could try as a test configuring a manual TCP/IP address instead of using DHCP. Try picking values similar to what your MacBook Pro is using including subnet mask, gateway and DNS.

Sep 24, 2019 4:18 PM in response to FWhite3

Have you tried moving the Ethernet to the top of the list in Network system preference? It currently shows WiFi at the top, but that may be just because it can't get Ethernet to work. Unlock the padlock at the bottom-left and click the gear for Set Service Order.

FWhite3 Author

Level 1

13 points

Sep 24, 2019 4:59 PM in response to Malcolm J. Rayfield

Thanks, but yes - I removed all the connections and added back only the Ethernet, with no success. FWIW, even the old Macbook has no problem seeing the Ethernet cable plugged in regardless of whether or not WiFi is turned on or ranked higher on the list.

hcsitas

Level 6

12,986 points

Sep 24, 2019 9:16 PM in response to FWhite3

At this point, my guess is that your router-closet has high EMR noise which later Macs are by design sensitive to. To prove this theory, get a cheap 4 port powered switch (~$12 on Amazon), connect it where the mini is and see if the LEDs on it come alive. If it does, stick with it and connect the switch to the wall. Good luck.

Sep 25, 2019 1:16 AM in response to FWhite3

A quick question: have you tried to reset the router etc to their factory settings? Or tried the new Macs in some other network? Or connect the Macs to each other with a cross-over cable (I don't know if you still need a special cable for this)?

Sep 25, 2019 1:28 AM in response to Matti Haveri

Matti Haveri wrote:

Or connect the Macs to each other with a cross-over cable (I don't know if you still need a special cable for this)?

Macs have had auto-crossover capabilities for many years. If however you connect two Macs to each other this way they initially will use self-assigned IP addresses beginning with 169. you can of course configure manual IP addresses.

FWhite3 Author

Level 1

13 points

Sep 25, 2019 5:52 AM in response to Matti Haveri

I haven't reset the router (other than power-cycling it), but I have taken it out of the loop entirely and just connected the computer to the modem directly (powering both down and up appropriately, of course). Didn't help. I haven't thought of the cross-over cable idea - may try that later today. Not sure how that would help with my problem exactly, but would be interesting to see if they see each other.

Sep 25, 2019 6:02 AM in response to FWhite3

This clearly is not the main cause since you have also experienced the problem with the router but…

Broadband modems are typically configured so they will only talk to the first device they see and will issue a single IP address to that device. They will then ignore subsequent devices which means those devices will not get and IP address and not be able to use the Internet.

The purpose of the router is to be the single device connected to the modem, the modem will then issue the router the IP address and the router will do NAT and allow multiple devices to share the connection. The router also normally acts as your DHCP server.

The fact you power cycled the modem should have resulted in it seeing the Mac mini as the 'first' device and have issued the Mac mini the single IP address.

(This is more for other peoples benefit, you clearly covered all the bases here already.)

As a reminder the single detailed report using ifconfig -m en0 indicated that Mac mini was a 10Gbps model. Did you do this on the other two? If they also show 10Gbps capabilities then it maybe as I suggested they all are 10Gbps models. It could be this is making them far more sensitive to issues such as cabling even if theory they should still work at 1Gbps. This might make the suggestion of getting a Cat6 or better lead worth trying.

New Macs will not recognize ethernet