Find a communication area on higher floor | Chapter 9 - Militarized Zone DI Riptide Guide
Last update: 11 May 2016
Return to the stairs. Head for the first floor and get to previously unreachable door. Ignore the central one, because they are barred. Approach the right one.
Defeat nearby Walkers. After that approach the right door leading to the room from which you see smoke is coming. Your objectives change.