Using the SOAP API Login() and Enterprise WSDL, I can login to our org with standard user types but can not login using a community users. Which AuthEndpoint should be set for community users?

// which authEndpoint should be used? None of the endpoints listed below will work for customer/parter users
          config.setAuthEndpoint("https://developer4-testcompany.cs18.force.com/services/Soap/c/35.0/0DF110000008OOO");
//          config.setAuthEndpoint("https://testcompany--testcompany.cs18.my.salesforce.com/services/Soap/c/35.0/0DF110000008OOO");
//          config.setAuthEndpoint("https://test.salesforce.com/services/Soap/c/35.0/0DF110000008OOO");
          connection = new EnterpriseConnection(config);