.. Closing the kitchen

Did you talk to Klaus? ( Some kind of vermin problem will shut the diner down for a while. )

Cause a vermin problem there. Did you notice there's also the backside of the diner?

There's the rat. Catch the rat.

Put the rat into the air vent.

Go back to the room 3 window and look into it. Otto will try to order some food, but fails. Next you should get him out of his room.