Wifi vs Ethernet

Primary interface is the first one in system preferences - network ( at least as far as I know)

 

All I know is that if you want to make sure Ethernet has priority, turn off the wifi. If you want wifi to have priority, which I wouldn't understand since Ethernet is usually faster, just unplug Ethernet. It is that simple.

 

i have the same speed and ping with the wifi like i have with the Ethernet, but my router is close (in the other room)

 

wifi AC rulz. The future is WIFI

 

1. Open System Preferences/Network.
2. In the left pane>bottom, click and hold the small black gear (context menu).
3. There you will find an option to "Set Service Order". Click that.
4. Then select & drag the options in your preferred order, with the primary being at the top.
5. Prior to quitting System Preferences, click on "Apply Changes".
6. Enjoy!

Note: While the selected services will not be operationally running simultaneously, that will be the order in which they are "on" and available.

 

With my iMac so close to the Airport Extreme, I prefer to run it wired. This leaves the WiFi open for everything else here that can't be wired to the network.

 

a Time Capsule can add 50 devices

 

This is the correct answer. The "Service Order" under the Network Preferences determines which interface will be configured for the default route on the routing table. This will be the interface used when trying to reach an address for which there is no other more appropriate entry in the routing table (or for which is not directly reachable on the local segment).

 

IMHO here's how I do it.
Use a quality simultaneous dual band router with GigE ports.
All stationary devices always use wired Cat-5e or 6 cable and disable the WiFi.
Put only your laptop(s) on 5GHz if possible. Your iOS devices and other gubbins on 2.4GHz

 

Only problem is the range on 5GHz might be shorter than 2.4, on the plus side AC is very very fast and beam forming and there tends to be less neighbourly WiFi chatter. Currently 802.11AC devices are few and far between.

I also have a AirPort Express (direct wired GigE from its WAN to LAN on AEBS) as an extender and AirPlay player. Although it's not AC it does allow for seamless roaming when I'm too far for the base station. One day I'll plug something into the APEs LAN port just to see if it bridges.

Another tip are those Ethernet over power adapters to get wired Ethernet when wiring is difficult. Although less than half the speed of GigE they do have a long range that can span several houses on the block (they won't go through the hydro pole transformers).

PS rule #4, never use your ISP's router / wifi they're often rubbish, always get one you can put in bridge or gateway mode.