*** BREAKING NEWS **** BB Link over WiFi works again!!!
Since the last time, I didn't used BB Link at all (because it worked only via USB cable), and today, I started BB Link, as usually my device was shown greyed out (not connected), and suddenly, it connects via WiFi and starts synchronizing stuff...
What has happened, I don't have clue, but probably something PC related, and it 'auto-solved' maybe with power-off-on, or due to some system update. Important thing is: it works now.
Folks, thanks for all constructive comments.