cellular-dataiphonewifi
I would like to use my jailbroken iPhone as a hotspot for my MacBook. It works well when my 3G internet is enabled. But when I disable it, the hotspot menu becomes unavailable… even if my iPhone is connected on the WiFi network.
I disabled the 3G to make sure it wouldn't use my 3G data plan.
Can I use my iPhone as a hotspot on WiFi (instead of 3G)?
If you plug any cellular enabled iOS device with Personal Hotspot turned on to a Mac via USB, the Mac will automatically open a network connection using the Personal Hotspot.
So yes, your Macbook Air will be the 1 connection you see.
The second part of your question is a little trickier and the answer is both complex and confusing but I will try to explain as best I can.
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Based on older knowledge with other multiple interface *nix systems is that it will be a complete toss up as to which connection your Mac will use since both active connections could possible provide the same route to the destination for any network query.
I have even seen, on both Windows and Unix networks, traffic coming in on one network connection and going out on another, which rarely works well.
To get round this, in the Network panel you could disable the "iPad USB" in your default location, but then set up a new location where your "iPad USB" is not disabled.
Finally, the order of your devices should mean that if your wifi is above the iPad USB device in your list when both are enabled, it will get priority over the hotspot, but there are still caveats and this could still use cellular data, but of a lesser amount.
You cannot use your Wi-Fi connection for Internet connectivity while other devices are using Wi-Fi for Personal Hotspot. You can share only a cellular data connection; you cannot share a Wi-Fi connection.
As seen here: http://support.apple.com/kb/ht4517
Best Answer
You can do this with USB or Bluetooth tethering on jailbroken iOS devices using an app such as MyWi. There are many other jailbreak apps for this function, so it's worth shopping around.
Some will only share the 3G internet connection, but I understand others will share any internet connection over USB or bluetooth.
You can't use wifi tethering to connect your computer to a wifi network your phone knows about.
The hotspot creates a new wireless network, but the iPhone is capable of attaching to only one wireless network at a time. It cannot connect to a wireless network with internet and create its own wireless network to share.
Since the iPhone is on the wireless network, though, you can get your computer on that same network since it will likely be in range.