your issue sounds like may be a proxy issue or possibly a device issue,for device issue try the following
>Go to Main Menu .
->Tap on Settings.
->Tap on General Settings .
->Tap on Reset .
->Tap on Restore all content
Also go to the general option and go to the ''manage application'' settings and clear the cache itunes apps and restart your device.
diff versions of itunes you have tried would not matter unless you have totally cleaned your pc of all old itunes files,simply removing it will not do that.
i would suggest to try to use one of the devices that "worked" and purchase something from the itunes store to rule out a network problem.
report back and let me know if any of that worked
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