Player can't connect to CMS

Hi,
I installed Xibo cms with docker on Debian Vm.
I have 6 networks.
The CMS is in XXX.16.XXX.XXX. For the player in the same networks it works. I can connect them to the CMS.
But for other, for example in XXX.17.XXX.XXX or XXX.18.XXX.XXX it doesn’t work.
I have a message : “Status Unable to connect to the remote server”.
I can’t ping them too.
The firewall rules are ok.
Someone can help me please ?
Sorry for my poor english.