Unable to use SSL or TLS to access OpenDirectory ldap server
The following were the steps I took to resolve this issue:

Reboot the server in safe mode (hold down shift key whilst restarting)

Let it idle for a while (apparently it is cleaning out caches in this mode)

Stop the existing slapd server

 sudo launchctl unload /System/Library/LaunchDaemons/org.openldap.slapd.plist


Set the correct certificate GUID in the file /etc/openldap/slapd_macosxserver.conf.  This can be ascertained from the contents of the /etc/certificates directory

sudo sed -e 's/oldguid/newguid/' /etc/openldap/slapd_macosxserver.conf &gt;/tmp/conffile
sudo mv /tmp/conffile /etc/openldap/slapd_macosxserver.conf


Remove the configured TLS certificate values from the file /etc/openldap/slapd.d/cn=config.ldif

sudo vi /etc/openldap/slapd.d/cn=config.ldif
remove any lines beginning with olcTLSCertificate


Start the slapd server again

 sudo launchctl load /System/Library/LaunchDaemons/org.openldap.slapd.plist


Reboot the server again into standard mode.

Then from a client computer with linux or mac osx check that you can connect via SSL and that the certificates are correct using the command

openssl s_client -connect ldap.yourdomain:636 -showcerts


If successful you will get a dump of your server certificates as well as a connection detail description:

No client certificate CA names sent
---
SSL handshake has read 5209 bytes and written 807 bytes
---
New, TLSv1/SSLv3, Cipher is AES256-SHA
Server public key is 4096 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1
    Cipher    : AES256-SHA
    Session-ID: C8E0F4A4ED24021DB4D98ACF5A9ACDC2293BC3961BF2AE90026115D899369E73
    Session-ID-ctx: 
    Master-Key: 
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    TLS session ticket:
    ...
    Start Time: 1400140597
    Timeout   : 7200 (sec)
    Verify return code: 0 (ok)


Some other notes:


Apple suggests that you can use self-signed and own certificate
chains (http://support.apple.com/kb/ht3745).  I use a self signed
chain and it is successful.
Port 636 is the standard ldaps port and is the port used by OpenDirectory (slapd)
TLS1 is supported as can be seen from the openssl connection test
Differing DNS names and host names do not matter (I tried both ways with a reboot between)
Differing reverse DNS does not matter (I tried both ways with a reboot between)