So you’re already 2 updates behind, not counting this one. I have an idea that when phones get two or more versions behind, they may fall out of eligibility for more recent updates.
As you know from reading the forum, swapping the SIM (different carrier) often helps. Here is a quite convoluted example (different phone but similar problem):
As you’re in France, try to borrow a Free SIM, I’ve never had update problems like that with mine.