To resolve this issue, identify which LDAP service is not accessible and remove it from the pool.
To identify which service is not accessible log in to the SSO Virtual Appliance and run this command:
nslookup server.com | grep Address | cut -f2 -d":" | xargs -I{} ping -c 1 {}
This should ping all the IPs resolved for the FQDN of the LDAP server and IPs that are not reachable. Ensure to remove unreachable servers from the pool.