From Berlin Brandenburg Airport (BER) to the apartment: 

(37 minutes) RE8 → S+U Alexanderplatz, change to M2 → Prenzlauer Allee / Metzer Straße, walk 5 minutes to the apartment

(46 minutes) FEX → Ostkreuz, change to S7 → S+U Alexanderplatz, change to M2 → Prenzlauer Allee / Metzer Straße, walk 5 minutes to the apartment

(57 minutes) S9 → S+U Alexanderplatz, change to M2 → Prenzlauer Allee / Metzer Straße, walk 5 minutes to the apartment

(64 minutes) S45 → S Schöneweide, change to S85 → Ostkreuz, change to S7 → S+U Alexanderplatz, change to M2 → Prenzlauer Allee / Metzer Straße, walk 5 minutes to the apartment

From Berlin Central Station to the apartment:

(18 minutes) S7 → S+U Alexanderplatz, change to M2 → Prenzlauer Allee / Metzer Straße, walk 5 minutes to the apartment

From Berlin Central Bus Station (ZOB) to the apartment:

(46 minutes) walk 12 minutes to S Messe Nord/ZOB, S41 → S Prenzlauer Allee, change to M2 → Knaackstraße, walk 5 minutes to the apartment