Nether Portal doesn't work

I was destroying an old nether portal and used the obsidian from this portal (portal A), to buuld a new portal in the coordinates 240,69,24 (portal B). But whenever I try to enter the Nether through portal B, it will get stuck at the loading screen and I'll end up disconnecting from the game. When I rejoin the server, I end up back in the moment when I'm still destroying portal A. Doesn't seem to happen to the other players, only for my portals