Steps to reproduce:
first i have installed zabbix server on my local ubuntu,
then i installed zabbix agent to my ubuntu and centos servers, i have modified /etc/zabbix/zabbix-agentd.conf, i have added my zabbix server ip (localhost,my public ip) and activated the tcp 10050
i connect to my zabbix server in web interface localhost then added the zabbix agents as hosts,
Result:
there is no connection or data sent, it says 111 refused connection and can't reach zabbix agent
see picture attached