hi, i'm operating an owncloud server that connects to an IBM Tivoli Directory Server as LDAP backend. the ldap admin tells me he is seeing "null binds" from my owncloud server in his logs: 2016-05-24T14:32:56.349452+2:00 srvr_ssl_read: EIO in handshake. EWOULDBLOCK timeout. Read: -2 of 0 2016-05-24T14:32:56.350445+2:00 GLPSSL019E The SSL layer has reported an unidentified internal error, SSL extended error code:406. 2016-05-24T14:32:56.351813+2:00 GLPSRV022E Failed to initialize secure connection from client (connection ID: 61786, IP address: x.x.x.x, Port: 59921). 2016-05-24T14:32:56.357220+2:00 GLPSRV044W Client connection from x.x.x.x bound as NULL closed by server. i investigated on my server and noticed that it has problems connecting to the ldaps://ldap.example.com uri (which is the ITDS server) under high client system load, whereas connection to ldap://ldap.example.com is ok. $ ldapsearch -v -x -z 0 -H ldaps://ldap.example.com -b "ou=groups,dc=example,dc=com" -v "objectClass=posixGroup" ldap_initialize( ldaps://ldap.example.com:636/??base ) ldap_sasl_bind(SIMPLE): Can't contact LDAP server (-1) my server (RHEL 7 on a ppc64 LPAR) is using the openldap clients/libraries. the high load that is causing the problems is on _my_ server. is there any specific tuning (besides increasing RAM/CPU) i can do to optimize ldaps client queries? i'm thinking of tuning the tcp stack or something similar, but i'm not an expert on this. where can i look for debug info? i have strace and tcpdump output thx matthias