Windows Server 2012 Core can only be locally managed by using the command line. This page contains a list of usefull commands on Windows Server 2012, these commands are not limited to the Core version.
Remove IPv6 binding from NIC
This command is the equivalent of unchecking the “TCP/IPv6” checkbox in your network connection properties.
Disable-NetAdapterBinding -InterfaceAlias "NIC Alias" -ComponentID ms_tcpip6
You can find the Interface Alias by using the following command:
Get-NetAdapter | Select-Object Name