How does OS X decide between Ethernet and Wifi for Internet access

4

When both are connected does it always use Ethernet or does it monitor both and use the most reliable or fastest one?

TheLearner

Posted 2015-09-21T11:38:24.857

Reputation: 2 333

Answers

6

It always uses the connection at the top of the service order.

To set the service order open System Preferences. Go to Network.
Click the cog at the bottom of the list of connections on the left hand side.
Screenshot:

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Then drag and drop the connections in the order you'd like them to be prioritised.
Screenshot:

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Click Ok, then Apply, and your wish is your Mac's command.

It's generally recommended that you set your cabled ethernet connections as higher priority than Wifi, as they are generally faster, will have lower latency, and aren't susceptible to interference. I personally like to set my USB iphone tether connections higher so I don't have to unplug or disconnect wifi to use 4G for uploading files in a hurry.

JackC

Posted 2015-09-21T11:38:24.857

Reputation: 86

Thanks JackC! This is fantastic. So does the OS keep all connections alive and then immediately switches when one drops? e.g. Ethernet goes down it switches to WiFi? – TheLearner – 2015-09-21T13:15:52.243

Yes. Exactly. You can connect to 2 different networks too. For example, maybe you're at work on your corporate network via ethernet, and you connect to your phone via wifi. If your connections are setup like mine, you'll be using the internet via the phone, but you can still connect to file shares on the corporate network via ethernet at the same time. – JackC – 2015-09-21T13:24:24.733

Sorry this might require another question but can I control which traffic goes to which or does it intelligently choose e.g. I attempt to access fileshare and it doesn't work on iPhone so it tries on ethernet? – TheLearner – 2015-09-21T13:31:00.093

1It should know which connection to use because of the network address. If both computers are on your phone's wifi hotspot, it's possible it'll try using the wifi. The best way to control it is by using manual IP addresses to connect to file shares. So you'll need to know the Ethernet IP address of the file share you want to connect to, and on your computer, you'll need to set Ethernet to a higher service order position than any other connection on that same network (ie wifi). – JackC – 2015-09-21T13:54:54.793

Asked: 2015-09-21T11:38:24.857

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Active: 2015-09-21T12:37:16.207