Stuck in a mission because of bug

I started a quest of captain zhingu, the quest requires me to go to haiju lagoon and to get there i need to go through the linnok couryard. however the gate in the linnok courtyard to the direction of that region is locked and i can't figure a way to get it opened. If one of you encountered this issue too please tell me how I can resolve it.

You need to talk to the gatekeeper.

Or if that doesn't help, do the primary quests (and the mission) until you can go past the gate.