ldapmodify -Y EXTERNAL failure - Confidentiality required (13)

This used to work... $ sudo ldapmodify -Y EXTERNAL -f 30logging.ldif SASL/EXTERNAL authentication started SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth SASL SSF: 0 modifying entry "cn=config" ldap_modify: Confidentiality required (13) additional info: stronger confidentiality required

The log says slapd[1266]: conn=6619437 op=0 BIND dn="gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth" mech=EXTERNAL sasl_ssf=0 ssf=71

This is my olcSecurity setting: olcSecurity: ssf=128 simple_bind=128

How would I fix this? It seems to be a catch-22.