Cant play when im not home!

ok so at home i can play nostalrius no problem and have a good time, but when i go back to school 2 and a half hours away, i cant play. im connected to the schools wifi and last year when i was at the same school, i played warlords of draenor no problem. but now, im connected to wifi and ill log in and i already have an account with 4 characters, when i log in it brings me to the page where you choose your language and what type of realm you want to play on, i choose english/normal and it says you "have been accepted to nostalrius begins realm" and i click accept and the realm lits pops up with the few realms that is on nostalrius, like the dev team and tester realms and such, but when i click enter on the nostalrius begins realm with my 4 characters it says connecting, then it goes back to the realm list almost instantly. its basically impossible to play, but im connected to the wifi and if the wifi was bad it wouldnt even let me log in, because when i log in it says connecting, connected, authentication successful, and all that really fast. im sorry for typing so much but i really wanna know why, the schools wifi was good enough to let me play the newest version of wow last year with millions of people, why cant i play nostalrius with only 8 thousand people? i dont understand. please help?