I've on my server attempted to recreate 'Animus Island' from AC: Revelations for the spawn point, and I have the tall portals in the back lead to rooms in separate worlds that include rules and tutorials and such. The issue is that those portals are open from two sides each, as they stand between two pillars, but for some reason you can only enter the portals through a certain direction, which, for some reason or another, is the back of the portal. It's not a server-stopping issue, but it is rather annoying.