Some of these specific boards, in some batches, have a problem that I saw being mentioned in various forums (https://www.mikrocontroller.net/topic/477142). To cut it short, the problem occurs if pin D12 makes contact with the ground (as shown by the green line). In this case, the board can be programmed normally but cannot connect to the network AT ALL!
However, the solution is quite simple if you have the tools. The problem arises at the point where the yellow circle is shown. There is a factory-made hole there, which I opened slightly more (with a 1 mm drill and 1-2 turns by hand!!) and the problem was solved.
CAUTION: Do not make the hole bigger than necessary!!! 1-2 turns are enough to scrape off the surface and remove the copper causing the short circuit, allowing the board to function. I hope I helped anyone facing a similar problem! Overall, the Board-aki works great (after the minor intervention, for which the Chinese factories are to blame!!), hence the 5 stars.