Similar as in https://issues.jenkins-ci.org/browse/JENKINS-24272 whenever we restart our master server we have to restart our mac jnlp slave (started via the jnlp file downloaded from the master). As indicated by dbeckham I'm opening a new issue.

The mac shows an error (see attached):
CouldNotLoadArgumentException[ Angegebene Datei/URL konnte nicht geladen werden: /var/tmp/javawsJt7vft]
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main.access$000(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.FileNotFoundException: /var/tmp/javawsJt7vft (No such file or directory)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(FileInputStream.java:195)
at java.io.FileInputStream.<init>(FileInputStream.java:138)
at java.io.FileInputStream.<init>(FileInputStream.java:93)
at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source)
... 5 more

java.io.FileNotFoundException: /var/tmp/javawsJt7vft (No such file or directory)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(FileInputStream.java:195)
at java.io.FileInputStream.<init>(FileInputStream.java:138)
at java.io.FileInputStream.<init>(FileInputStream.java:93)
at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source)
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main.access$000(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)

When started via the cli (as described on the master's client website) the reconnect works.