I wanted to update from 3.1.2 to 4 IOS
with a great iphone 3GS unlocked and just a little problem of loosing wifi when I restarted

Because of the unlocking problems I followed Olethros suggestions (thanks to him for his patience)
launched TinyUmbrella with my SHSH blob , run their server
upgraded my iphone 3gs from 3.1.2 to 4.2.1
then with pwnagetool I updated to 4.2.1,

Everything went fine but after the pawnage my service was lost
I checked my firmware that should have been the same 5.11.07 3Gs I had before
but alas it changed to 5.14.02.
Wasn't TinyUmbrella supposed to save my unlockable baseband and keep the same one?!?

My iPhone 3gs looked for service for ever, waiting for an activation that never came
After 15 min I restored it back to what was working before ( 4.2.1) and I got everything working again
(TinyUmbrella was in the back still running and I could read the log about connecting and bla bla )

Tried a second time to jailbreak it again but this time no way
It was stuck on restore in progress and the iPhone was pitch black
nothing going on there
From TinyUmbrella I click Fix Recovery
and this time I went back and was able to restore to the normal firmware 4.21 by Apple and not my custom one.

What shall I do?
I read everywhere but could not find an answer
Thanks if someone could give me a hint

I'm very sorry that you misunderstood my explanation regarding what TinyUmbrella was used for on the 3GS

I said very clearly you needed to use custom IPSW (I didn't specifically say made by pwnagetool as sn0wbreeze can also make custom IPSW that prevents baseband updates). Depending on the app, you may need to specifically tick an option that says something like "prevent baseband update". This is the case with sn0wbreeze, however *most* versions of pwnagetool prevent baseband update by default. There are exceptions, but this is usually when there is a good reason for allowing baseband update.

In addition, because you are restoring to an iOS version that apple no longer issues a SHSH blob for, you need to run tiny umbrella (or point your hosts file at Cydia) so that iTunes can get a SHSH blob for iOS 4.2.1 - This must be done for BOTH custom IPSW and Apple IPSW (as Apple no longer signs 4.2.1 restores for the 3GS)

You *MUST* have upgraded to iOS 4.1 to get the baseband you refer to.

The reason you now have issues with restores to 4.2.1 is that apple changed the restore procedure so that it fails if there is a baseband mismatch (4.2.1 should have baseband 5.15.04) and you need to use fix recovery to exit.

Ohhhh
Your post 05-25-2011 12:05 PM

Originally Posted by Olethros

When you say you have a saved SHSH, you do understand you need a unique SHSH blob for each iOS version.You can use TinyUmbrella's TSS Server to trick iTunes into accepting locally saved SHSH blobs.

I'm not an expert and you did not specify that did not work with 3gs
What shall I do now? Why the jailbreaking does not work? It is a custom firmware 4.2.1 made using pwnagetool. I'm now with 4.2.1 but it is un-pwned.

BTW when I built the custom firmware, preserve baseband was grey
Please tell me what to do now
Thanks