Ok found the issue:
[root@mail configs]# tail -f /var/installatron/logs/error_log
#5 /usr/local/installatron/lib/boot.php(29848): itron::init()
#6 {main}
2017-05-07T13:21:58+02:00 Linux PHP 5.6.30 /usr/local/installatron/lib/boot.php(21770): Warning: fileowner(): stat failed for /home/client11
Since client11 now has web server in server2, it's not possible to use Installatron anymore.
There is no link between Kloxo-MR servers seen from Installatron...
Installatron has discontiued the support for Kloxo
We need to contact Installatron devs to convince them to add support for Kloxo-MR. They might not be aware of Kloxo-MR is actively developed!