Hello, I live in Madrid - Spain and my ISP is Movistar. I can´t enter the game and when I check the Spanish forums are many many people with the same problem and all of us have Movistar. In our region seems to be a problem with Movistar. I don´t know what really happens.
Your ISP likely goes through Telia as well. Telia is absolutely terrible. There have been many issues with that provider over the past few years. Nothing Blizz can do about it.