Stefan is at the Gates of Kapia. Reny needs to open the gate for him.
Zimulis won't do it. Maybe Robbi can be made to do it.
Unlike normal walkthroughs, in Nice Game Hints you can select just the puzzle you want hints for. Here are listed the puzzles for "Level 1 - Reny" in Kapia. The guide you choose only contains information about that puzzle, reducing possible spoilers for other puzzles.