Why won't my iMac connect to Ethernet?

Is an add-on “coffee shop” VPN installed? If so remove that, restart, and test again.

Is the Ethernet patch cable you are using verified in another install, and with all eight wires? Older and slower cables can have fewer wires, and some patch cables are just bad.

Any add-on security apps, add-on anti-malware apps, add-on firewalls, or related apps? If so, boot into Safe Mode and test the network connections again.

How many IP network routers are installed in your local environment? This includes purpose-built routers, managed switches with so-called “layer 3” routing features, and Wi-Fi routers not already configured as access points.

How did you check the function of Ethernet wall socket? With a pin-continuity and wiring-test tool, with a connection by a different Ethernet device and cable, or by verifying the cable was latched, or some other means?

GPT tools are computationally-expensive statistical guess-the-next-word word schemes, with corpora of questionable and outdated information, and are not particularly reliable reference sources. GPTs are mechanisms ideally suited for administrative sabotage and related activities, however.

You have changed the Connection Order Preferences to Ethernet from Wi-Fi correct?

If not, the Mac will connect to Wi-Fi.....even if the Ethernet signal from the router is OK.

System Preferences > Network > Set Connection Order

Make sure that Ethernet is at the top of the Connection Order list. If it's not....drag Ethernet to the top.

fowllanguage wrote:

I connected it to my iPad via usbc and it immediately connected like it’s supposed to.

Hmm, I'm trying to understand what you did here. Are you saying that when you connected your iPad to your iMac via USB-C, the Ethernet connection on the iMac starting working ... but, when you remove the iPad, it stops?

What is the make & model of your router? When your iMac is connected by Ethernet, is that connection directly between the Mac and the router, or is the Mac connected to an Ethernet switch that is connected to that router? ... or some other configuration?

if it was me then I would suspect the router being the culprit, some models have to actively be set to bridge 5Ghz/2.4Ghz and wired ethernet so maybe it's not set up to provide internet to the wired ethernet

but of cause it can also be a defect ethernet port in your map and of cause if you connect to the uplink port in the routers switch or the likes

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