How to have a session that never expires ?

I have some questions and comments...what version of CI are you using?  Your session settings appear to be correct. Although only one of my cookie config settings is different: $config['cookie_domain'] is set to ''.  Did you check your PHP.ini Session settings?

Thanks for your help, i use the 3.1.6

Before, the cookie_domain was see to '' and it was the same issue, i just changed it recently cause i found someone on Stack Overflow who recommended it, but it didn't fix anything 

this is the extract of my phpinfo() for the session, first value is the the local value, second is the master value.
If you see something abnormal, don't hesitate to tell me

The only diff are session.cookie_domain, session.cookie_httponly, [b]session.name,  session.save_handler, [b]session.sid_length and [/b][/b]session.use_strict_mode.

session.auto_start
Off
Off
session.cache_expire
180
180
session.cache_limiter
nocache
nocache
session.cookie_domain
.mydomain.com
no value
session.cookie_httponly
On
Off
session.cookie_lifetime
0
0
session.cookie_path
/
/
session.cookie_secure
Off
Off
session.gc_divisor
1000
1000
session.gc_maxlifetime
1440
1440
session.gc_probability
1
1
session.lazy_write
On
On
session.name
ci_session
PHPSESSID
session.referer_check
no value
no value
session.save_handler
user
files
session.save_path
/srv/data/var/php/www
/srv/data/var/php/www
session.serialize_handler
php
php
session.sid_bits_per_character
5
5
session.sid_length
32
26
session.upload_progress.cleanup
On
On
session.upload_progress.enabled
On
On
session.upload_progress.freq
1%
1%
session.upload_progress.min_freq
1
1
session.upload_progress.name
PHP_SESSION_UPLOAD_PROGRESS
PHP_SESSION_UPLOAD_PROGRESS
session.upload_progress.prefix
upload_progress_
upload_progress_
session.use_cookies
On
On
session.use_only_cookies
On
On
session.use_strict_mode
On
Off
session.use_trans_sid
0
0