You never said... So I had to ask for clarification.
See, that is a more full explanation. However, your 930 is not an AT&T branded 830. Things often vary by model, Region, etc.
Yes, it is hopeless for me to comprehend. :winktongue:
According to the documentation the device must be debranded and flashed to the Poland CV. AT&T branded Lumia 830 can not be debranded. A very excellent and knowledgeable flasher/debrander/cross variant match selctor named pankaj981 lead me through a series of experiments via Registry Hack and we were unable to debrand an AT&T 830. Perhaps you know a way?
None of the comments I've looked through (and by no means have I read all 140+) have indicated success without debranding or on a current ROM other than Poland CV. Do you have evidence otherwise?
With all due respect, your experience and the contents of that web site do not address the OP's issues directly.
OP confused GDR2 update with Denim update in the first place. Then PepperdotNet made it clear to OP that he is wrong, and Denim was never available through Windows Insider Program; but also made a false statement that Windows Insider trick (to get a confused update) is not available at all.
That's why I quoted only the last part of his statement. Thought it will be clear enough.
I was able to get GDR2 update few days ago on my unbranded 930, and it was (or is) available to other devices also (including branded ones). I went through all the comments.
If Microsoft didn't fix it yet, it's still there... It's definitely not carrier nor region dependent. When the loop was firstly exposed about two months ago, everyone was able to get the GDR2 update.
EDIT: I can not help you. In EU you're free to debrand your phone with tools such as Nokia Product Support Tool, and Lumias don't have simlocks.