phpVirtualbox console button grey out

Hello comunity,

I am trying to use Virtuabox plugin on my OMV.
On PHPVirtualbox, VM starts, I can see it on the preview windows but the console button is grey and unclickable.

As my NAS has been always upgraded since OMV 0.4 (I am now in 2.1.18), I tried to purge every virtualbox packages and reinstall them but there is no changes.

Any idea?

It is running

[13:53:19] root@openmediavault:/media/939bc22d-2090-4b82-908e-16a2b6c7a348/NAS$ service vboxweb-service status
Checking for VBox Web Service ...running

same behavior with both chrome and firefox.
I saw that even with purge done, the PHP Virtualbox admin password still the one I've set on OMV 0.5, some config files still there?

I try with backport kernel, same thing

Edit: Shame on me! It was a problem of layer 8 of the osi model, on display, remote server was disable.