Nostalrius Begins - Quality wow vanilla realm (1.12)

Hello, whenever i take the Zeps from SV to undercity, or the other way around, i just fall down and die when it's about to load. And when i take the other zeps i am just ported to the tower on the other side, which is fine, but weird. Although the bug where i cant go to SV or undercity is really troublesome. Is it something i can fix myself?