KNOWN ISSUE: Error while establishing a nonsecure connection on port 636
SYMPTOMS
Creating a connection to a profile on port 636 with the "Use secure connection (SSL)" box unchecked results in either Error 52: "Unavailable" or Error 81: "Server Down" every time a connection attempt is undertaken.
CAUSE
LDAP Administrator version 3.0 and later is working over the Microsoft LDAP API that in turn interacts with the Windows sockets and Microsoft Schannel. However Microsoft Schannel handles all communications on port 636 as secure and creates an SSL client credential that introduces misunderstanding between the LDAP server expecting a nonsecure connection on port 636 and client API that is suggesting its SSL client credential. This problem is a result of Microsoft Schannel interfering with nonsecure communications on port 636.
WORKAROUND
If it is possible to configure the server so that it accepted nonsecure connections on any other port, but 636, then it will solve the problem. Another way is to configure port redirection using iptables or ipchains so that LDAP Administrator established the connection on a port different from 636 and the connection was redirected to the server port 636.