On the K1000 appliance go to Settings -> Control Panel -> User Authenication
Check that all the existing LDAP server profiles to have correct LDAP settings
Even if you are not using the shipped examples of the admin and read only admin profiles, please have a valid IP address entered for all LDAP server profile or the K1000 appliance will wait to timeout on an invalid IP address.
If using Orgs in the K1000, please make sure that other Orgs have valid IP addresses on their own LDAP profile as well.