Problems starting SUM on Netweaver Java

Hello colleagues,

I recently installed Netweaver 7.4 (java only) and now want to patch Java. As I read, JSPM has been obsolete since 7.2 and has been replaced by SUM.

So I installed SUM on my Netweaver host.

The problem now is, that I can call the SUM application on http://<hostname>:4239 , but when the Java banner comes up, nothing happens and I recieve the following error message on OS - Level:

java.net.SocketTimeoutException: Read timed out...

How to to go around this Socket Timeout?

Thanks in advance