Home Network driving me bananas. WiFi works perfectly. Connecting router to Mac via Ethernet causes Mac to crash

My original speculation was about power over Ethernet (PoE), but looking at the Orbi manuals, I see no mention of that. So please disregard that idea.

Am I correct with this partial summary? You have three Mac mini machines. I’d like to call them A, B and C for simplicity.

  • Mac A belongs to your wife. It behaves as expected wrt the Orbi network.
  • Macs B & C both show the problem described, although only when connected via built-in Ethernet port.
  • They both show the problem independently (ideally here, you’d power off & disconnect Mac B, demonstrate that the problem occurs with Mac C, then vice versa).
  • Macs B & C are identical models: “Mac mini (2018)”.
  • Mac A is a different model of Mac mini.
  • Macs B & C are running different operating systems (one Catalina, the other Monterey),
  • … but with very similar configuration and data (since Migration Assistant was used to set one of them up).

Assuming that’s all correct (particularly “they both show the problem independently”), I think possibilities for a cause here include:

  1. an incompatibility between the Orbi hardware and specifically the 2018 Mac mini (Macs B & C) hardware;
  2. damage to the Ethernet ports on both Macs B & C (lightning or other power surge could be a common cause here, although it seems pretty unlikely to me that both would still be mostly working afterwards);
  3. configuration on both Macs B & C (something copied across by Migration Assistant).

My guess is that 3 is the most likely, but this does seem an unusual problem, so good to systematically rule out causes where possible.

I have more thoughts about possible approaches to this, but I’ll hold off until the above is acknowledged.

One quick idea though: is System Preferences > Sharing > Internet Sharing perhaps enabled on Macs B & C?

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the solution indicates that you were right. Please see below.

Thank you so much !! I am extremely grateful for your analysis and didactic post.


@paalb @trilo @ashley @chirano @mpainesyd @markwmsn

Hello all,

I am extremely grateful for all the thought and time you put into my problem.

After having tried everything under the sun, the solution initially proposed by the excellent @paalb and described in https://www.lifewire.com/reset-network-settings-on-mac-5184072 (solution 1) worked perfectly thanks to @paalb ’ s clear instructions . To avoid misleading you, I have been testing it all day and night **on both minis **and no glitches.

For the benefit of anyone who encounters the same problem:

• open system preferences → Network just so it’s ready for quick access
• disconnect cable Internet from mac (including HUBs, adapters, etc)
• turn off WiFi
• plug Ethernet cable into Mac port and immediately (before computer crashes) go to Sys Pref → Network→ click on the Ethernet connection → click on (-) → apply → (+) (create new Ethernet).
• Test: click on app store to see if blank, and test Internet speed.

There is one point that still puzzle me. This is an academic question because everything works.

When I compare the Internet speed of the now working mac Ethernet port and that of the Ethernet port of the USB-C thunderbolt docking station, the Docking Station has a speed of 370 Mbps whereas the actual Ethernet port on the mac has a speed of only 240 Mbps, so I actually end up using the thunderbolt docking station port.


I’m glad the problem has been beaten into submission.

Is there a reason why it would be necessary to connect the Ethernet cable and then delete the Ethernet service? In other words, why could you not select and delete the Ethernet service in the Network pane, then connect the cable and create a new Ethernet service?

For that matter, why do you need to delete the original Ethernet service at all? I have multiple Ethernet services on my primary Mac. (Back when I created them, it seemed that each adapter required its own service. Maybe that has changed; maybe not. Now I use one almost exclusively, but the others do not seem to bother anything.) It seems like you could have simple created a new service. (I don’t recommend this, because I see no reason to keep a wonky service around, but I think it should be possible.)

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thank you for your post.

1- if nothing is plugged into the mac Ethernet port, as far as I understand, there is no Ethernet connection visible and nothing to delete. I am strictly referring to the mac Ethernet port. Other “ethernets” are visible, namely the thunderbolt ports.

2- I am not sure what would have happened had I created an Ethernet service without deleting first.

3- deleting → re-creating the Ethernet is simple and involves no configuration. If I started to create new ethernets, I was concerned about bungling the configuration and making matters worse.

Would you happen to have any idea why the thunderbolt docking station’s Ethernet is faster than the mac native Ethernet port ?

There are different speed Ethernet ports, eg. 10/100/1GE/10GE.

  • Mac Mini is likely 1GE.
  • Thunderbolt 3 is likely 10GE.
  • Your max internet speed falling somewhere in between.

Plus the computer hardware itself will apply some limits (bus speed, etc).

Assuming you’re using the same cable to test both? That could also be a factor.

I know little about such things, but I can have multiple ports for Ethernet. In the following screenshot, they are inactive (and there is one active Ethernet port but it does not have Ethernet in its name), but I have had multiple Ethernet ports active at the same time. None of them, however, is built in; they are all adapters. Maybe the built-in port is different.
Screen Shot 2022-09-11 at 17.18.00

That basically is what I do with the USB Ethernet ports. I create them and they work. There are some parameters that I could change; I leave them at the default values.

I know less about Thunderbolt than I do about Ethernet. Sorry.

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Yes this is the case for thunderbolt or USB ports but not for native Ethernet mac ports according to my testing.

I don’t understand why you go to the trouble of creating them. In my experience they self create the moment you plug the Ethernet cable into the Ethernet USB adapter

By thunderbolt I basically mean USB C because that is how the dock is connected to the mini

thank you

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yes absolutely. thank you for the info.

Thanks; I learned something.

Well, yes, that’s how I create them, and that’s the only time I create them.

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pleasure talking to you

Just a suggestion re POE systems. Most homes have a 220 volt input from the power company. And various rooms are split up so the normal load balance is almost equal, meaning 1/2 of outlets may be on one side ( 110 volts “A” side ) and other outlets ( 110 volts on “B” side )

Depending on local wiring codes, etc and a nearby transformer- Satellite units on the “B” side may not pick up the POE signal from the “A” side. Thus the ethernet poe may not work for you. ONE possible way to check is to plug in your router and via an extension cord, plug in one satellite on the same plug to start and see it it works on ethernet and wi fi. Then use anouther outlet in the same room with same satellite, check it out. IF all works well with that satellite, take it to other rooms and try. Do not be surprised IF in a different room, wi fi works and etherrnet does not.

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very interesting. I will do the test.
You seem to be very knowledgeable, so I have one question.
In the past year, I have had 3 troubleshooting incidents which turned out to be caused by some noname Ethernet cables I bought (nothing to do with the current situation).
I was going to buy an Ethernet cable tester. Prices range for $20 to $500. Are they useful ? Can you suggest any reliable brand (hopefully not expensive).
thank you for your very interesting post

You’re confusing terminology. “POE” is “Power Over Ethernet”. A way of carrying DC power over Ethernet wires so remote devices plugged into your wired network don’t need to also be plugged into line power.

You are describing a powerline network, where data is carried over your AC power lines.

Reliable data transmission across the two phases of residential power was a problem a long time ago, when the tech was using low bandwidth systems like X10. With those systems, back in the day, you would sometimes need to install a repeater to move data between the two phases. These devices would plug into a 220v outlet (e.g. one meant for an electric clothes dryer), so it has access to both phases, and they include a pass-through plug so you can continue to operate the device that normally uses the outlet (like your dryer).

But modern powerline networks (typically based on HomePlug AV2 operate at high enough frequencies that this isn’t a problem. In your service panel, the two phases are very close to each other (with an air-gap between them) and as such they form a capacitor. Capacitors like this can pass high frequency signals (like your powerline data) with no problem, even though low frequencies (like the 60Hz AC power) doesn’t pass.

As such, most homes have no problem passing data across the two phases when modern powerline network adapters are used.

I suppose you might have a strange wiring setup where your two phases are going into two different service panels - that wouldn’t allow data to pass between the two phases. But I’ve never ever heard of a home wired in this fashion.

But none of this is applicable in this context. The OP is talking about problems with Ethernet, not a powerline network. And the problem appears to have been fixed through macOS configuration changes.


Depends on what you expect.

Your cheap $20 testers are just going to be a continuity tester. They will let you know if the connectors are mis-wired, but they won’t tell you if the cable is capable of supporting the bandwidth you plan to run through it. It might be useful for quick spot checks, but they are not what I would consider a proper test.

The expensive testers will run a variety of high frequency signals to test whether your cable run can actually handle some specific bandwidth (e.g. gigabit, 10G, etc.) I personally believe that these devices are so expensive that it’s not worth the cost unless your career involves installing and testing networks.

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thank you. I confused you because I changed topics. I just wanted to seize the opportunity to ask another question. After the initial post I googled POE:
thanks again

very useful answer. thanks very much. You explain very well the levels of testing.

Thanks for the correction to my terminology. but there is no way to know the age or power routing of this persons home or apartment power system- added to the mess is the relative new use-requirements for circuit breakers with built in ground fault capabilitiy. We have such in our apartment, and they do strange things such that they are slowly being replaced with ‘new’ and ‘improved’ breakers on a 5 year old apartment complex. And the fubar mess of our built in coax , phone, and ethernet plugs could easily be part of a several weeks study course as to what should never be done for any kind of ’ service ’ . The result is I’ve set up my own router for wi fi and ethernet and voip phone service run off one of the two coax lines that work -AFTER an $80 service call from comcast which bypassed the super cheapo patch panel which split incoming coax into 6 outlets ( thus 1/6 of signal ) and added a filter- And I then abandoned the ether net and phone patch portions.

Unless his building is so ancient (e.g. over 100 years old) that it doesn’t have normal two-phase power, a modern powerline network adapter shouldn’t have a problem.

Do you have experience that demonstrates otherwise?

GFCIs shouldn’t affect or be affected by powerline networks. Those devices work by comparing the current on the hot line against the current on the neutral line. They trip if there is a difference (which means that there is a ground fault somewhere on the circuit causing current to leave the system in a way that it shouldn’t).

Powerline adapters don’t interfere with this. They draw current like any other device - the current on the hot lead equals the current on the neutral lead. They don’t redirect current to other circuits or to ground wires. They modulate the power’s 60Hz signal to carry the data. Devices not participating in the powerline network simply see these signals as “noise” (which is why you must always plug a powerline adapter directly into a wall outlet and not use a surge suppressor or a UPS - their built-in power filters will strip the data).

Arc-Fault interruptors (AFCIs) are a bit trickier. They look for signal patterns that resemble an electrical arc somewhere on the circuit. The signals produced by a powerline adapter don’t resemble an arc in any way, but we do know that first-generation AFCI breakers were too sensitive (e.g. fluorescent fixtures can make them trip), so if you have those, it is conceivable that a powerline adapter might make them trip. But if you have some of these first-generation AFCIs, it is more likely that other stuff in your home will cause spurious trips before your network equipment does.

FWIW, I replaced four first-generation AFCI breakers in my home with newer ones because lighting fixtures were making them trip. The newer AFCIs have had no problems with those same fixtures. The two remaining AFCIs that don’t have lights on the circuit have never tripped, despite my using powerline networking throughout the house for nearly 10 years in this home.

Unfortunately, low-voltage wiring like these are often installed by people with little or no knowledge or certification. But that’s not the case for power lines, where every state has some pretty strict regulations for licensing electricians.

In my home, I’ve got two coax circuits. One is a direct line to my office, for Comcast to connect to my cable modem, with no splitters. The other is for my satellite TV, where the three rooms are connected to two incoming lines via a few specialty splitter-like devices (see my next post, since this one is getting pretty long. Although the house has a built-in Coax splitter, it is meant for old-fashioned analog cable TV and is useless for anything modern, so it is not connected to anything and likely never will be connected to anything.

We have Cat-5 wiring in our walls, used for the analog phone jacks, but they’re not connected to anything. There’s a panel where they all come together, but since we don’t subscribe to a land-line, they do nothing. I considered using the wires for Ethernet, but they don’t go to all the rooms where I want to put equipment, so I’m continuing to use the powerline adapters.

It would be nice to use our coax cabling for data, but that’s not possible in our situation. The MoCA standard would give us plenty of bandwidth, but we can’t combine the coax segment from Comcast with the one from Dish Network, because they use overlapping frequency ranges, and there are no MoCA bands available that wouldn’t interfere with one or the other. So that’s a project for the future if/when I decide to disconnect the satellite TV and therefore have all the coax available for a single network.

For those who are curious, here’s a description of the way Dish Network satellite TV is wired in my home.

What I’ve got in my home is pretty much the right side of this image (ignore the “equipment at the tripod” section):

(h/t DISH TV for RVs | rvSeniorMoments )

  • The dish on the roof has two coax cables that enter a “Solo Node” device bolted to the side of my house. This combines the two downleads into a single coax cable that enters the house.

  • The coax from the solo node enters a very interesting splitter-like device called a TAP. The tap combines and splits several very different kinds of signals, allowing a minimal number of cables, and to be compatible with existing in-wall cable TV cabling:

    • Power is delivered from the Hopper (the main satellite tuner, DVR and network hub) through the TAP and the solo node to the dish’s LNBF.
    • Satellite data is delivered from the LNBF through the TAP to the Hopper.
    • MoCA data (including digitized TV) used to connect all of the devices. It carries (I think):
      • LNBF control data from the Hopper to the LNBF, so it can select the appropriate satellite frequencies.
      • Digital TV data from the Hopper to the Joeys for watching live TV and playing DVR-hosted content.
      • IP networking data for on-demand content.
  • The two Joeys (remote receivers) connect to the TAP via a standard bidirectional splitter, similar to what modern cable and fiber systems use.

  • The Hopper is the Internet gateway for everything, connecting to my LAN (and its powerline network) via Ethernet. (Wi-Fi is also available, but Ethernet works better for me.) It also allows remote access so I can stream my DVR content and watch TV from anywhere in the world via Dish’s web site and mobile app.

Sadly, there is no way to combine its MoCA network with Comcast’s cable. Although Comcast also supports MoCA, they are using different frequencies, so there would be no way to eliminate the powerline/Ethernet and use a single MoCA network for everything without getting really funky (e.g. an Ethernet switch and two MoCA transceivers in order to bridge the Dish network with the Comcast network).