So, suddenly my phone would only lock on GPRS/EDGE and denied to go on HSDPA/3G/4G. Completely out of context at that time I thought to dirty flash a new nightly of the Carbon ROM that I had already downloaded, and the problem was solved!!! Booted in android, and boom connected to 4G..
It happened again during the following days, and every time a dirty flash of the next nightly would fix the issue. Without a logical explanation for my understandings, but it just fixed the problem.
Now, since yesterday, it is not recovering with the above technique so it's time to seek further into the issue! With your help of course