Suddenly, yesterday, one of my apache servers became unable to connect to my LDAP (AD) server. I have two sites running on that server, both of which use LDAP to auth against my AD server when a user logs in to either site. It had been working fine two days ago. For reasons unknown, as of yesterday, it stopped working. The error log only says this:

auth_ldap authenticate: user foo authentication failed; URI /FrontPage [LDAP: ldap_simple_bind_s() failed][Can't contact LDAP server], referer: http://mysite.com/

I thought perhaps my self-signed SSL cert had expired, so I created a new one for mysite.com, but not for the server hostname itself, and the problem persisted. I enabled debug-level logging. It shows the full SSL transaction with the LDAP server, and it appears to complete without errors until the very end when I get the "Can't contact LDAP server" message. I can run ldapsearch from the commandline on this server, and I can login to it, which also uses LDAP, so I know that the server can connect to and query the LDAP/AD server. It is only apache that cannot connect.

Googling for an answer has turned up nothing, so I'm asking here. Can anybody provide insight to this problem?

Here's the LDAP section from the apache config:

<Directory "/web/wiki/">
    Order allow,deny
    Allow from all
    AuthType Basic
    AuthName "Login"
    AuthBasicProvider ldap
    AuthzLDAPAuthoritative off
    #AuthBasicAuthoritative off
    AuthLDAPUrl ldaps://domain.server.ip/dc=full,dc=context,dc=server,dc=name?sAMAccountName?sub
    AuthLDAPBindDN cn=ldapbinduser,cn=Users,dc=full,dc=context,dc=server,dc=name
    AuthLDAPBindPassword password
    require valid-user
</Directory>