multiplexer failed for client

Classic Servoy
1

Hi all,

we are suddenly getting a lots and lots of these:

Exception, see log file for full details: Received fatal alert: certificate_unknown
2013-06-04 15:28	multiplexer-reader-a321d9a[SSL_NULL_WITH_NULL_NULL: Socket[addr=/xx.xxx.xx.xxx,port=50511,localport=1099]]	ERROR	com.sebster.tunnel.impl.zb	multiplexer failed for client cfbfc092-0ffa-4216-a1ac-c6eeb442a952

Server Information
Servoy version 6.1.4 -releaseNumber 1429
Port used by RMI Registry: 1099
Repository version 42 (38D33764-DF89-469A-9DDD-0E009CF128D2)
Current time: Tue Jun 04 15:33:20 BST 2013 
Uptime: 7 minutes 52 seconds 

JVM Information
java.vm.name=Java HotSpot(TM) 64-Bit Server VM
java.version=1.6.0_45
java.vm.info=mixed mode
java.vm.vendor=Apple Inc. 

Operating System Information
os.name=Mac OS X
os.version=10.7.5
os.arch=x86_64

Windows clients.

Any ideas?

2 
SEVERE: Couldnt export object with port from server, trying to do on anonym port
javax.net.ssl.SSLPeerUnverifiedException: peer not authenticated
    at sun.security.ssl.SSLSessionImpl.getPeerCertificates(SSLSessionImpl.java:397)

in Java Console on Mac OS X