Depending on your configuration, you may notice that the iPad or iPhone simulator uses the LAN connection. One workaround is to unplug your ethernet cable so that the simulator will be forced to use WiFi, but if you don't want to do this every time, you may also try the following configuration below:
1. Go to Network Preferences
2. Click the Gear icon and choose "Set Service Order"
3. Move the Wi-Fi service on top of Ethernet service.
You can restart the simulator and see if it uses the Wi-Fi connection.