Personally, I feel that if this were such a big issue relating to the update, it would have been resolved. Samsung has not shied away from stopping updates or has arguably been pretty good at fixing these issues. TBH, my personal opinion is that the network provider is the issue or your personal hardware, as that's the only logical explanation I can see, given that this isn't a mainstream issue and seems to affect very few users. If it were an update issue, it would affect everyone, or at least those with the same device—or your phone's receiver is faulty.
Im absolutely not meaning to/ have no intent to say youre wrong- as that woudnt be fair to say when Im not in your shoes.
But, I'm sure if this is a big enough issue where you believe it's an update issue, your post will get plenty of attention and responses.
Hope you the best in figuring this out.