How do I configure mobile home folders on 10.6.8 server?

I'm trying to set up mobile home folders on a Mac Mini (microceratops.local) OS 10.6.8 server for some laptops (running Lion and Mountain Lion respectively), but I seem to be having some basic difficulties.

Some oddities: I'm being alerted that microceratops.private has an expired/not trusted certificate. Is this relevant to my issue? Generating new ones doesn't appear to fix the issue.

User password types are all set to Shadow Passwords, but most of my online reading suggests that Open Directory must be enabled, and that OD must be the user password type. However, I cannot change this for any user because "Cannot set record to Open Directory because you are not an Open Directory password server administrator. In order to select Open Directory, your own password type must be Open Directory. Administrators with other password types cannot set a user’s password type to Open Directory." But my admin acct. has the popup for User Password Type set to Shadow Password and is grayed out (in other words, unchangeable). Here I'm stymied.

Server Admin tool reports that Open Directory isOpen Directory Master, LDAP is running, and Password server is running (do I need Kerberos? This is just for a small home network.) LDAPSearch Base: dc=microceratops,dc=private

LDAP appears to be running. I can go to any client laptop and connect to microceratops.home via System Preferences (under Accounts). But I cannot connect to any account on microceratops.local from any of the MacBook Pros' login windows. (Normal connections via filesharing or VNC work fine).

What am I not doing correctly here? Thanks for reading this far.