iPhone 4 tethering / personal hotspot does not work

How to fix your iPhone tethering

This FIX is for both :-
 
iPhones using tethering via USB connection.
iPhones using personal hotspots using Wireless connection.

At KMS we experienced an issue with our company iPhones' Internet tethering and personal hotspots.

When we are away from our UK head office we often use our iPhone Internet connection to relay data back to our head offices.
Whilst off-site using our Internet tethering on our iPhone (via USB or Wireless personal hotspot) we experienced an issue where this option was no longer available in our iPhone menu!

After speaking with Apple technical support and getting nowhere our IT support eventually figured out how to resolve the problem.

Firstly speaking with Apple support - they will only tell you to do the following processes:-

1. Turn your phone off and on again.
2. Take your SIM card out (wait 10 secs) put it back in and re-start your iPhone.

(This did not work)

1. Press and hold both the on/off button and 'home button' simultaneously for around 10 seconds until the apple logo appears.
2.  This should re-set all your network connection details

(This did not work)

1. Go to the settings -> General -> Reset. Here select Network Settings.
2. Confirm the re-set (your phone will restart itself)

(This did not work)

Finally Apple will then suggest to do a full backup of your iPhone.
Then do a 'Full iPhone restore'.
Both of these require iTunes and most imporantly an Internet connection. If you do not have an internet connection it will not do a complete restore leaving your iPhone useless and unusagable until you have an Internet connection.
(We tried this and it still did not work.)

Finally from our own IT support specialist at Kingston Marine Services Ltd a solution was found.

To explain - The tethering and hotspot options disappear from your main settings menu. (Or become unusable via the 'settings->general->network' menu)

Firstly our IT support managed to get Apple support to admit this problem is a KNOW BUG! in Apples' most recent update firmware version (affecting this OS firmware: iPhone3,1_5.0.1_9A405_Restore.ipsw) 

Our IT guy's explanation:

It seems that when an application is installed (some apps) install a 'profile' this profile contains a security certificate used for varifying the apps install.
By removing the 'profile certificate', this fixes the issue with internet tethering and personal hotspots for both USB connection and wireless connection.
To remove the profile follow these instructions :-

HOW TO FIX YOUR IPHONE TETHERING!

Goto Settings -> Profile : When you see a profile listed tap the option to 'remove'.
Once this profile security certificate is removed you will notice your iPhone tethering now works as it should. iPhone 4 Now FIXED!
 
The options which had 'disappeared' will now be displayed in their correct locations.
(you may need to restart your iPhone to see the menus)

Hey Presto problem fixed - now wasn't that much simpler than spending ours doing a a FULL backup and restore!

You can now use your iPhone for your internet connection once again.
This allowed us to send vital information back to our head offices located half way around the world when other communication methods were not available.

Kingston Marine Services Ltd are fanatical about providing support to our customers. After-all we don't want to sitting dead in the water without a paddle ;-)
So for any other Skippers, Engineers, Marine engineers or communications officers KMS hope this little bit of information helps.

For all your Marine Diesel maintenance and repair works please contact KMS at www.kingston-marine.com

Happy Sailing!

Kingston Marine