1) The host or the zero clients are not connected to the LAN/Internet.

Resolution: Connect the zero clients to the LAN/Internet, and make sure the network is fine.

2) The zero client is with a new firmware version while the vMatrix Server Manager version on the host is out of date.
Resolution: Upgrade the vMatrix Server Manager.

3) IP Addresses in the DHCP pool have been used up so that new connected zero clients cannot find hosts in the LAN while the old connected zero clients do not have the problem.

Resolution: Go to the DHCP setting page and enable more IP addresses or shorten the time of IP address tenancy.