1 user account can log on at a time

[eluser]brianw1975[/eluser]
Look in application/config/config.php

Code:

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

You can try changing $config['sess_match_ip'] = FALSE; to TRUE, but judging how effective that is would be tough.

Did you do a search on the forums? This same question was asked just a couple of days ago.