I recently had some trouble getting my MacBook to connect to the Internet via an iPhone over Bluetooth. It worked fine for a while, then began disconnecting only a second or two after connecting. If you’re having the same problem, read on. If not, skip this post.

Context: My MacBook runs OS 10.5.7, and I’m trying to connect to the Internet via the Bluetooth connection and the “tethering” feature on an iPhone. The phone runs on the Rogers network.

I first went through the standard setup for tethering — turn on tethering, turn on Bluetooth, “pair” your devices — and everything went perfectly. Then, about a day later, things stopped working. The “Connect to Network” entry on the Bluetooth menu became grayed out. The Bluetooth Preferences showed the MacBook/iPhone connection fnctioning briefly when you manually turned the connection on, and then disconnecting after a few seconds. Green light for two seconds, then red light.

I am pretty sure the problem started after I plugged the iPhone in with the USB cable and then accepted prompts to create a new network connection. Everything went pear-shaped from that point on. I tried removing the network connections through the Bluetooth Preferences and Network Preferences UIs, to no avail.

After much digging, here’s a recipe that  solved the problem for me:

[on MacBook] Remove the device pairing: open Bluetooth preferences, select the iPhone entry, click the minus sign.

[on iPhone] Remove the device pairing for your Macbook: Settings, General, Bluetooth, select the device, click ‘Forget this Device’.

[on MacBook] Rename the directory /Library/Preferences/SystemConfiguration to something else, e.g. SystemConfiguration-old.

[on MacBook] Reboot. Mac OS will rebuild the SystemConfiguration for you.

[on MacBook] Run through the standard iPhone tethering setup steps again.

You might want to give it a shot if nothing else works. I assume no liability for any damage you might do.

Other references that might help you:

• This comment suggests deleting only preferences.plist, rather than the whole SystemConfiguration directory.
• This Apple support forum thread describes the problem but doesn’t offer a solution.
• Another Apple Support page discusses other tethering problems. iPhone: Troubleshooting Internet tethering

Good luck. Tethering is great when it works!