How to get to Zeuthen from airports of Berlin

Connection between airport Berlin-Tegel
and DESY-IfH Zeuthen

Take bus #128 in front of airport exit. Leave at "Kurt-Schumacher-Platz" (about 10 min. ride, a panel in the bus shows always the next stop).
Walk downstairs to subway line U6. Choose direction "Alt-Mariendorf". Leave train at "Tempelhof" (about 30 min. ride)
Walk upstairs to city train station with same name. Take line S46 direction "Koenigs Wusterhausen". Leave train at station "Zeuthen" (about 30 min. ride).
The exit from the platform is backwards w.r.t. train direction, only. Walk downstairs, turn RIGHT, walk upstairs and about 100 m to next crossing. Turn right (now you should have the direction of your train) and walk to the 3rd street on the left side (= "Platanenallee"). Turn left and walk the last 100m, institute is on the right side. Total walking time about 10 min.

Take bus #109 in front of airport exit. Leave at city train ("S-Bahn") station "Charlottenburg" (about 12 min. stations, not all with a necessary stop, but a panel in the bus shows always the next stop).
Walk forward to the S-Bahn station (150 m). Walk upstairs to platform with direction "Westkreuz" or "Potsdam". Ride 1 station to "Westkreuz".
Change train line by walking upstairs to top level platform. Take line S46 direction "Koenigs Wusterhausen". Leave train at station "Zeuthen" (about 45 min. ride).
as above

Take subway line U6 in front of airport building ("Platz der Luftbruecke"). Choose direction "Alt-Mariendorf". Leave train at 2nd station ("Tempelhof").
Continue with item 3 of above.

Leave the airport building and look over the (big) parking place. In about 300 Meter distance (slightly left-oriented) there is the railway and city train station "Schoenefeld". You can walk there or take the shuttle bus directly in front of the airport exit. In the station take any CITY train (S-Bahn) on either side of the platform.
Go 3 stations to "Adlershof" and leave the train. Change to the other side of the platform and wait for the train S46 to "Koenigs Wusterhausen". (Opposite direction !) Leave train at station "Zeuthen" (about 15 min. ride).
The exit from the platform is backwards w.r.t. train direction, only. Walk downstairs, turn RIGHT, walk upstairs and about 100 m to next crossing. Turn right (now you should have the direction of your train) and walk to the 3rd street on the left side (= "Platanenallee"). Turn left and walk the last 100m, institute is on the right side. Total walking time about 10 min.