Add a simple quest (that can be done at any time) so players can open the 3 mage door alone, you added quests to open the other player required doors so do the same here. This is so annoying for players that dare to pick Windy as their starting nation.

If you skip 3-2 (which you allow players to do) they can't get this done before the mission where the gate is needed to be passed. At a bare minimum, don't let players skip 3-2 anymore.