Hrvatska Internet?

Hi, im not from Croatia, but we own apartment in Ciovo, Gornij Okrug. We are using this aparmťent 3 months in year (in summer). I love it here, but we have slow internet. We got router from A1, but its garbage. Even when i have A1 on mobile phone, its very slow. I noticed when i changed operator to “TM HR” the connection ist better. My question is TM HR = T mobile? Or is it something diferent? Thank you