Comment 4 for bug 1104476

The certificate authority is missing. You may want to add it to the configuration in NetworkManager to point to a CA certificate that can be provided to you by your network administrator:

Jan 24 21:28:21 ubuntu wpa_supplicant[3569]: wlan0: CTRL-EVENT-EAP-METHOD EAP vendor 0 method 25 (PEAP) selected
Jan 24 21:28:21 ubuntu wpa_supplicant[3569]: TLS: Certificate verification failed, error 20 (unable to get local issuer certificate) depth 1 for '/C=SK/L=Bratislava/O=Comenius University/CN=WWW Servers Certification Authority/emailAddress=xxxxxxxxx'
Jan 24 21:28:21 ubuntu wpa_supplicant[3569]: wlan0: CTRL-EVENT-EAP-TLS-CERT-ERROR reason=1 depth=1 subject='/C=SK/L=Bratislava/O=Comenius University/CN=WWW Servers Certification Authority/emailAddress=xxxxxxxx' err='unable to get local issuer certificate'
Jan 24 21:28:21 ubuntu wpa_supplicant[3569]: SSL: SSL3 alert: write (local SSL3 detected an error):fatal:unknown CA
Jan 24 21:28:21 ubuntu wpa_supplicant[3569]: OpenSSL: openssl_handshake - SSL_connect error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
Jan 24 21:28:22 ubuntu wpa_supplicant[3569]: wlan0: CTRL-EVENT-EAP-FAILURE EAP authentication failed

I've noticed this too happening with self-signed certificates in universities. The alternative is to edit the connection file in /etc/NetworkManager/system-connections to remove "system-ca-certs=true".