CI Session - Lost connection to MySQL server during query

My site is working fine but sometimes it suddenly starts giving CI_SESSION error...

Error is : 

Code:

ERROR -> Query error: Lost connection to MySQL server during query - Invalid query: SELECT `data`
FROM `ci_sessions`
WHERE `id` = '44278e7a05ed07842bgf15b1a5feaff0dcee76c3'

ERROR --> Query error: MySQL server has gone away - Invalid query: INSERT INTO `ci_sessions` (`id`, `ip_address`, `timestamp`, `data`) VALUES ('21440e7a66ed02342bbf15b1a3feaff0dcee76c3', 'xxx.xx.xx.xx', 1545006351, '')

ERROR - --> Query error: MySQL server has gone away - Invalid query: SELECT RELEASE_LOCK('5d966d065ca3606e9cdf23c761035e54') AS ci_session_lock

 Please let me know if anyone has any idea about this...
 
 My config setting is : 

Code:

$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 7200;
$config['sess_expire_on_close'] = TRUE;
$config['sess_encrypt_cookie'] = FALSE;
$config['sess_use_database'] = TRUE;
$config['sess_table_name'] = 'ci_sessions';
$config['sess_match_useragent'] = TRUE;
$config['sess_time_to_update'] = 300;
$config['sess_driver'] = 'database';