iMac Ethernet failed; access Ethernet LAN devices via Wi-Fi?

Question

iMac Ethernet failed; access Ethernet LAN devices via Wi-Fi?

Hi Apple experts!

I have been using an ethernet LAN to communicate between an iMac, laptop and Mac Pro, with a printer, all connected via a Netgear Switcher to an NX510V 5G router for internet access. However, following a recent thunderstorm the ethernet port on the iMac has died - not recognised by the Switcher, and no connectivity. I've eliminated all external issues (cables etc). The rest of the network is working fine.

On the iMac I can connect to the Router via WiFi for internet access, but I lose connectivity to the printer and file sharing with other Macs. I can use a USB to Ethernet adaptor, and the network functions again, but I really need the USBC port for an external hard drive.

Strangely the laptop is connected solely via Wifi, but file sharing works to the other devices, and to the iMac when the iMac is connected via the USB-Ethernet adaptor - I have never tested the printer from the laptop. I can't see what's different in the settings for the iMac and laptop, other than different OS's - the laptop and Mac Pro are on Sequoia 15.7.7, and the iMac on Sonoma 14.8.7.

Is anyone able to point to settings (either on the iMac or in the NX510) to allow a connection via Wifi to access the devices connected via Ethernet, please? I understand that all devices should be connected to the same LAN, but the 5G router should be the common point, so I must be missing something.

Thanks in advance for any ideas.

Martin.

iMac 27″

Posted on Jun 27, 2026 8:51 AM

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Answer 1

Jun 27, 2026 9:10 AM in response to martinnichols

First, have you tried connecting the iMac to a different port on the Netgear switch? If you are lucky, the damage may be to the switch port and not your iMac's port.

If you determine that the iMacs port is the damaged one you may as well delete that interface to prevent the iMac from being confused. System Settings > Network > select "Ethernet" > click "Delete Service" button.

Then, put your iMac and laptop next to each other and visit System Settings > Network > Wi-Fi > Details.... Then select TCP/IP on the left to see the configuration. Make sure that the "Router" is showing exactly the same IP address. If it is not, report back here what you see on that page for each and someone can better diagnose the issue.

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Answer 2

Jun 28, 2026 3:44 AM in response to martinnichols

Many thanks for all the suggestions.

I'd already eliminated the Switcher being at fault - the same cable from the same switcher port when used (with appropriate adaptors) worked perfectly with a laptop, and the iMac itself via USBC, and LEDs behave exactly as expected.

Similarly, iMac SMC and NVRAM already reset, and TP Link firmware checked as up to date. Router rebooted several times too, for good measure.

There's no sign of any damage to the iMac ethernet port. Perhaps I've been unlucky, but my previous 2019 Mac Pro had an ethernet port that slowly died - it went through a period of intermittent connectivity for a week or so, before complete failure. Maybe a component batch fault, as it and the 2020 iMac were made around the same time...

FishingAddict - thanks for your suggestion: it does look like the iMac might have been intermittently connecting to a guest network on the TPLink at startup. Obviously the internet worked fine in that case, but with no access to the rest of the network. Removed the default 'auto-join' from the guest network, and it now seems to be working as it should.

Thanks again. I'll update if the plot thickens.

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Answer 3

Allan Jones

Level 10

81,800 points

Jun 27, 2026 10:17 AM in response to martinnichols

If you have not done so yet, I would start with resetting the SMC on the iMac: Reset the SMC of your Mac - Apple Support

Can you see any evidence of arcing in any of the ports involved?

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Answer 4

MrHoffman

Level 10

155,971 points

Jun 27, 2026 10:49 AM in response to martinnichols

Check for firmware updates.

I think the following document applies to your particular TP-Link NX510v AX3000 (probably, guessing) router:

https://static.tp-link.com/upload/manual/2024/202402/20240206/1910020945_BBA%20MBB%20Routers_UG_REV1.0.0.pdf

See page 142.

Might also want to check in a TP-Link forum for details around available multicast forwarding options (for mDNS / Bonjour) or related restrictions, as TP-Link seems to call that.

You’ll want the Wi-Fi first in the service order list in macOS, too.

And if the Ethernet port is fried, who knows what might be fried or might glitch? I had a very expensive server too close to lightning strike, and it was never right from that day onward.

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Answer 5

Jun 27, 2026 10:26 AM in response to martinnichols

Allan Jones makes a great point. Inspect both the Ethernet cable ends as well as the switch and iMac Ethernet ports looking for any scorch marks that may indicate arching occurred. Another indicator that power damage occurred is when one of more switch port link lights remain on despite nothing being plugged into them (always a bad sign).

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Answer 6

den.thed

Level 10

95,638 points

Jun 27, 2026 9:29 AM in response to martinnichols

I recently had a D-Link Switch go south on my local Ethernet Network setup.

The Ethernet Switch did not completely fail, so it took a little longer to pinpoint the actual problem.

1) Test a direct Ethernet connection between the iMac and your other networked devices.

2) Make sure that all of your cables are at least Cat 5e or shielded Cat 6.

3) Test each cablesto make sure that all of the pairs are working.

3) Test another Switch in your Ethernet Network.

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