XMPP error with jabjab.de

I have problems to get the XMPP binding running with jabjab.de server. I tested my accounts with other client and all works. But openhab (1.8.3) gives this error:

[ERROR] [tion.xmpp.internal.XMPPConnect] - Could not establish connection to XMPP server 'jabjab.de:5222': Remote host closed connection during handshake [WARN ] [nhab.action.xmpp.internal.XMPP] - Could not send XMPP message as connection is not correctly initialized! [WARN ] [o.j.smack.tcp.PacketWriter] - Exception writing closing stream element java.net.SocketException: Socket closed at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:116) ~[na:1.8.0_91] at java.net.SocketOutputStream.write(SocketOutputStream.java:153) ~[na:1.8.0_91] at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221) ~[na:1.8.0_91]

my openhab.cfg looks like this:

### XMPP Action configuration ### xmpp:servername=jabjab.de xmpp:securitymode=required xmpp:tlspin=CERTSHA256:a28d93db3de8bfa37e707877334991ec4452eefacc7ff68adfdd4f1fd5556698 xmpp:proxy=jabjab.de xmpp:port=5222 xmpp:username=OpenHabName xmpp:password=*************** xmpp:consoleusers=empfaengername@jabjab.de

The tlspin is taken from this page:

My Java version is:
Java(TM) SE Runtime Environment (build 1.8.0_91-b14)
running on:
3.16.0-44-generic x86_64 GNU/Linux

Any idea what’s wrong?