By default, the Enterprise Server's 'Default Computer Policy' (or any custom created configuration policy) will not be applied on the Enterprise Server itself.
Client Automation - All versions
Configuration Policies can be applied only if a DSM Agent is present on a machine and since there is no Agent present on the Enterprise server any configuration policy change will not be applied on the Enterprise Server.
Install a DSM Agent on the Enterprise Server pointing to a Domain Manager of your choice (with 'CAF SETSERVERADDRESS <domain manager>').
Once the DSM Agent is installed, the Enterprise Server will show up under 'All Computers' on the Domain Manager.
Create a new policy on the Domain Manager with the desired policy settings and distribute the policy to the Enterprise Manager unit listed under 'All Computers'.