SMTP Error: Could not authenticate

Hello,

I am getting the following log when trying to send a test email. Any help/advice would be greatly appreciated!

Connection: opening to smtp.gmail.com:587, timeout=300, options=array ()
Connection: opened
SMTP -> get_lines(): $data is ""
SMTP -> get_lines(): $str is "220 smtp.gmail.com ESMTP a4sm9159847ioa.43 - gsmtp"
SERVER -> CLIENT: 220 smtp.gmail.com ESMTP a4sm9159847ioa.43 - gsmtp
CLIENT -> SERVER: EHLO endpoint0016d443.chios.panth.io
SMTP -> get_lines(): $data is ""
SMTP -> get_lines(): $str is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]"
SMTP -> get_lines(): $str is "250-SIZE 35882577"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577"
SMTP -> get_lines(): $str is "250-8BITMIME"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME"
SMTP -> get_lines(): $str is "250-STARTTLS"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-STARTTLS"
SMTP -> get_lines(): $str is "250-ENHANCEDSTATUSCODES"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-STARTTLS250-ENHANCEDSTATUSCODES"
SMTP -> get_lines(): $str is "250-PIPELINING"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-STARTTLS250-ENHANCEDSTATUSCODES250-PIPELINING"
SMTP -> get_lines(): $str is "250-CHUNKING"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-STARTTLS250-ENHANCEDSTATUSCODES250-PIPELINING250-CHUNKING"
SMTP -> get_lines(): $str is "250 SMTPUTF8"
SERVER -> CLIENT: 250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-STARTTLS250-ENHANCEDSTATUSCODES250-PIPELINING250-CHUNKING250 SMTPUTF8
CLIENT -> SERVER: STARTTLS
SMTP -> get_lines(): $data is ""
SMTP -> get_lines(): $str is "220 2.0.0 Ready to start TLS"
SERVER -> CLIENT: 220 2.0.0 Ready to start TLS
CLIENT -> SERVER: EHLO endpoint0016d443.chios.panth.io
SMTP -> get_lines(): $data is ""
SMTP -> get_lines(): $str is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]"
SMTP -> get_lines(): $str is "250-SIZE 35882577"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577"
SMTP -> get_lines(): $str is "250-8BITMIME"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME"
SMTP -> get_lines(): $str is "250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH"
SMTP -> get_lines(): $str is "250-ENHANCEDSTATUSCODES"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH250-ENHANCEDSTATUSCODES"
SMTP -> get_lines(): $str is "250-PIPELINING"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH250-ENHANCEDSTATUSCODES250-PIPELINING"
SMTP -> get_lines(): $str is "250-CHUNKING"
SMTP -> get_lines(): $data is "250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH250-ENHANCEDSTATUSCODES250-PIPELINING250-CHUNKING"
SMTP -> get_lines(): $str is "250 SMTPUTF8"
SERVER -> CLIENT: 250-smtp.gmail.com at your service, [2001:4801:7829:102:be76:4eff:fe10:ddd]250-SIZE 35882577250-8BITMIME250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH250-ENHANCEDSTATUSCODES250-PIPELINING250-CHUNKING250 SMTPUTF8
Auth method requested: XOAUTH2
Auth methods available on the server: LOGIN,PLAIN,XOAUTH2,PLAIN-CLIENTTOKEN,OAUTHBEARER,XOAUTH
CLIENT -> SERVER: AUTH XOAUTH2 dXNlcj1zbW9ydG9uQG1pbmRncnViLmNvbQFhdXRoPUJlYXJlciB5YTI5LkdsdmRBeEhTdllhcThWSDl5TWJoY1A4YUU0VVdxdWJSTm1uWTlSSG5BalFlVFVzMl9TZ0JzRW1nYlB6NjRabGZGSEItUDR4djhhYWlqT002S1ZvSjIwMW05RTIwdVZwa2hDMjIybllNWlBvbVhrYVNaOXdEbU5yLW1IUzYBAQ==
SMTP -> get_lines(): $data is ""
SMTP -> get_lines(): $str is "334 eyJzdGF0dXMiOiI0MDAiLCJzY2hlbWVzIjoiQmVhcmVyIiwic2NvcGUiOiJodHRwczovL21haWwuZ29vZ2xlLmNvbS8ifQ=="
SERVER -> CLIENT: 334 eyJzdGF0dXMiOiI0MDAiLCJzY2hlbWVzIjoiQmVhcmVyIiwic2NvcGUiOiJodHRwczovL21haWwuZ29vZ2xlLmNvbS8ifQ==
SMTP ERROR: AUTH command failed: 334 eyJzdGF0dXMiOiI0MDAiLCJzY2hlbWVzIjoiQmVhcmVyIiwic2NvcGUiOiJodHRwczovL21haWwuZ29vZ2xlLmNvbS8ifQ==
SMTP Error: Could not authenticate.
CLIENT -> SERVER: QUIT
SMTP -> get_lines(): $data is ""
SMTP -> get_lines(): $str is "535-5.7.8 Username and Password not accepted. Learn more at"
SMTP -> get_lines(): $data is "535-5.7.8 Username and Password not accepted. Learn more at"
SMTP -> get_lines(): $str is "535 5.7.8 https://support.google.com/mail/?p=BadCredentials a4sm9159847ioa.43 - gsmtp"
SERVER -> CLIENT: 535-5.7.8 Username and Password not accepted. Learn more at535 5.7.8 https://support.google.com/mail/?p=BadCredentials a4sm9159847ioa.43 - gsmtp
SMTP ERROR: QUIT command failed: 535-5.7.8 Username and Password not accepted. Learn more at535 5.7.8 https://support.google.com/mail/?p=BadCredentials a4sm9159847ioa.43 - gsmtp
Connection: closed
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting

Server Info

OS: Linux endpoint0016d443.chios.panth.io 4.4.31-201.fc22.x86_64 #1 SMP Wed Nov 16 04:31:58 UTC 2016 x86_64
PHP version: 5.5.24
WordPress version: 4.7
WordPress multisite: No
openssl: Available
allow_url_fopen: Enabled
stream_socket_client: Available
fsockopen: Available
cURL: Available
cURL Version: 7.40.0, NSS/3.21 Basic ECC