Don't have any experience with the java web console but have you checked to make sure it's listening on the right address?
netstat -an | grep LISTEN | grep 6789
and make sure that it shows something like
tcp 0 0 *.6789 *.* LISTEN
if it's only listening on local host (127.0.0.1.6789) then you will need to tweak the config to listen on all addresses or change it to listen on your 188.8.131.52 address.
also are you running any firewalls?