At this point, you may change to any job for the rest of this quest.
Travel to Nashmau and speak with Dnegan at H-6 on the second floor for a cutscene. During the cutscene you will be asked three questions.
On the first question choose either "Ask about getting around Nashmau" or "Invite him to drink some tea". Selecting "Ask about the automaton" ends the cutscene and you will need to return another game day to complete the quest.
On the second question choosing either Chai or Coffee will work.
On the third question "the cup with a suspicious VAPOR" is the correct choice.
Run to the Iron Gate at J-10 and open it up with the Lamian Fang Key and continue running directly north through the area to J-8. Open the door there and go through. From there, go north and find the tunnel entrance at I-6. Go East and then take the fork going south in the tunnel back to Caedarva Mire.
Shortly after you exit, click on the ??? for a cutscene.
Make sure to not drop or you will have to walk through Arrapago Reef again.