The console fails to connect to server

Hi,
I did search the forum and have not found an answer to my problem:
The console fails to connect to the server, instead showing code - see attachment.

I submit a screenshot of the console from the browser and the debug log.

I have OSX 10.11.3 where I also run OSX server 5.0.4 on a MacPro.

java version "1.6.0_65"
Java(TM) SE Runtime Environment (build 1.6.0_65-b14-468-11M4833)
Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-468, mixed mode)

Please help

Stef

[zip]

try to wait a bit before opening the console, after the Mac starts up

I have left it for hours, it doesn't seem to do the trick. Also, the log is the same even when I do not try to access the web console.