If your organisation are using stricly Kerberos authentication, the SEP server requires a SPN (Service Principal Name) entry.
For advanced users:
Please specify the service class as: SEP
Serviceclass and host are required, but port and service name are optional. The colon between host and port is only required when a port is present.
More detailed explanation:
A service principal name (SPN) is the name by which a Kerberos client uniquely identifies an instance of a service for a given Kerberos target computer. If you install multiple instances of a service on computers throughout a forest, each instance must have its own SPN. A given service instance can have multiple SPNs if there are multiple names that clients might use for authentication. For example, an SPN always includes the name of the host computer on which the service instance is running, so a service instance might register an SPN for each name or alias of its host.
Our Professional Services Team does not offer Kerberos support, however we can offer some useful links to get you going if you are experiencing this issue:
MS technet Wiki - Service Principal Names (SPNs)
MS technet - Registering a Service Principal Name
MS technet - Setspn overview