iMac prefer ethernet over WiFi

[josduc]

I have my 2017 iMac hooked up with an ethernet cable, which obviously gives me speeds of approximately 1 Gbit/s. Useful for me for file transfers in my network etc.

Recently I got myself a Watch Series 3, which I use to unlock the iMac. This requires WiFi to be enabled on the iMac. So far so good, unlocking works 99% percent of the time.

The problem is since I enabled WiFi on the iMac, it often picks the WiFi adapter instead of the ethernet adapter for my network. It happens when I make the iMac go to sleep and wake it up, but not all the time. I can disable wifi and the ethernet adapter picks up the connection just fine, but it's annoying.

I can't figure out what I'm doing wrong, or maybe I'm not and it's just a bug. What have I tried so far:

• Adjust the order of the adapters in the network settings (ethernet on top, WiFi on bottom)
• Reset PRAM
• Reset SMC
• Reinstall MacOS (10.13.2)
• Give the ethernet adapter a fixed IP, dns, router address, and the WiFi adapter automatic DHCP
• Give the ethernet adapter a static IP address in the router
• Safe boot MacOS

The last two I tried to exclude the ethernet adapter getting an IP address slow form the router. Which means the WiFi adapter gets an IP before the ethernet adapter so MacOS picks it as preferred.

Anything else I can try? Maybe some .plist I can trash?

 

[macnmac]

that personal internet service or work internet and what ISP?

 

[Superspeed500]

Maybe you should take a look at using the networksetup command from terminal? You can type man networksetup to open the manual page for that command.

 

[nambuccaheadsau]

Remove the Ethernet Cable and leave it wifi at those speeds you lucky devil. Rural Australia a morose, penny pinching right wing Federal Government keeps us on old copper wire with a download speed of 5-6MMb/ps!!

 

[josduc]

Haha, no my internet connection is "just" 200 mbit down and 20 Mbit/s up. Ziggo, The Netherlands. Though I do file transfers in my own network to and from my NAS. And my wifi is 217 Mbit/s while ethernet gives around 1 Gbit/s

I had a look at the network setup command.

(1) Ethernet
(Hardware Port: Ethernet, Device: en0)

(2) iPhone USB
(Hardware Port: iPhone USB, Device: en5)

(3) Thunderbolt Bridge
(Hardware Port: Thunderbolt Bridge, Device: bridge0)

(4) Bluetooth PAN
(Hardware Port: Bluetooth PAN, Device: en4)

(5) Wi-Fi
(Hardware Port: Wi-Fi, Device: en1)

 

[BurgDog]

Happens to me too and I have set the order for ethernet first in the preferences/network/set service order settings. Gets the proper adapter on boot but something picks wifi after sleep resume. Annoying as the speed difference is quite notably slower on wifi. Turning off wifi then back on corrects it until the next time it gets screwed up. This is, of course, on my internal network so has nothing to do with my internet connection. I assume ethernet is slower to restart after resumes so looks like wiki gets picked but that should correct itself when the primary adapter goes online. I have a lot of stuff on a storage server connected to the net so speed does matter even with a good wifi, ethernet is much faster.

 

[josduc]

Happens to me too and I have set the order for ethernet first in the preferences/network/set service order settings. Gets the proper adapter on boot but something picks wifi after sleep resume. Annoying as the speed difference is quite notably slower on wifi. Turning off wifi then back on corrects it until the next time it gets screwed up. This is, of course, on my internal network so has nothing to do with my internet connection. I assume ethernet is slower to restart after resumes so looks like wiki gets picked but that should correct itself when the primary adapter goes online. I have a lot of stuff on a storage server connected to the net so speed does matter even with a good wifi, ethernet is much faster.

I have two separate SSID's for my wireless; one for 2.4 GHz and one for 5 GHz. You can alter the order in which MacOS picks a wireless network. What I did yesterday was put the 5 GHz SSID as top, and 2.4 GHz as second. Guess what, so far so good, the iMac picks my ethernet adapter first now... Hope it stays this way!

 

[BurgDog]

I have two separate SSID's for my wireless; one for 2.4 GHz and one for 5 GHz. You can alter the order in which MacOS picks a wireless network. What I did yesterday was put the 5 GHz SSID as top, and 2.4 GHz as second. Guess what, so far so good, the iMac picks my ethernet adapter first now... Hope it stays this way!

Hope it works for you. Didn't for me as that is how I've been setup for the last couple of years and I still get WiFi as default sometimes after resumes. I expect funny timing issues as the cause as resume restarts hardware and may be different for various configurations. I'm using the built-in stuff on my 2013 Mac Pro to connect. Only reason I have WiFi turned on at all is for Apple watch unlocks and location services.

 

[Bbeelzebub]

I've had the issue a couple times where it changes the order of my preferred networks. I am on wireless as the speed is identical in my house whether I am on ethernet or at the 5GHZ wifi band. Every so often, I notice the net is slower and check it and sure enough, it has switched to the 2.4 ghz that gives slower speeds.

Last time I checked it, I noticed a bunch of networks that I've connected to on my iPhone were on the list again as well (I had deleted them a few weeks ago.) Somehow, iCloud kept restoring the old settings. I reset them and removed the not used networks again and haven't had a problem since.
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Hope it works for you. Didn't for me as that is how I've been setup for the last couple of years and I still get WiFi as default sometimes after resumes. I expect funny timing issues as the cause as resume restarts hardware and may be different for various configurations. I'm using the built-in stuff on my 2013 Mac Pro to connect. Only reason I have WiFi turned on at all is for Apple watch unlocks and location services.

Do you have to be on WiFI for that to work? What frequency? I read that Gen 1 Apple Watches (which is what I have) can only really use 2.4Ghz and not 5Ghz. I haven't bothered setting up my watch to unlock the computer because I strictly use 5Ghz internet and assumed I'd have issues.

 

[josduc]

Yes, WiFi has to be turned on for location and unlocking with the Watch. Unlocking the Mac with a Series 3 Watch works like a charm when a 5 GHz is selected on the Mac.

The workaround of selecting the 5 GHz instead of the 2.4 GHz still works here. It's a bit of a hack but why not.

I was wondering @BurgDog if tampering with the WiFi settings would help. In Network, WiFi, Advanced, TCP/IP tab, you can set it to manual. What happens if you set the IP and Router to 127.0.0.1? Maybe also for DNS?

*edit: just tried and MacOS won't let you enter an IP that starts with 127... Right. So I just put in a bogus IP 169.0.0.1, same for router, nothing near the range of the DHCP pool. Unlocking works! It picks my Ethernet as network adapter! Location Services works! Does this work for you?

 

[BurgDog]

Thanks for the advice, I changed mine to 169.0.0.1 as well and so far location services and watch unlock work. I will take some time to make sure my wifi doesn't try to take over after resumes as the problem is random and doesn't happen on all resumes.