I had similar problems in 8. Even though I had static leases set in DHCP, oftentimes services come up before the IP address has been obtained. The physical console and SSH worked, but not XOA nor XCP center.
Set a static IP address and reboot.
If that does not work, repeat the installation and set a static IP at install.
Make sure your IP address has not changed and look at the lease time. Is it only leased out for a few minutes?