zabbix-agent2 doesn't start after boot

[m4km1k]

After reboot zabbix-agent doesn't start:

# systemctl status zabbix-agent2
zabbix-agent2.service - Zabbix Agent 2
Loaded: loaded (/usr/lib/systemd/system/zabbix-agent2.service, enabled)
Active: inactive (dead)​

Each time I have to:

service start zabbix-agent2 

I have on docker on mariadb agent2.

I've check systemctl and it's enable

root@db1:/etc/systemd/system# systemctl is-enabled zabbix-agent2
enabled 

when i try to manually stop and start its hangs up.

systemctl stop zabbix-agent2
systemctl start zabbix-agent2 

There's nothing interesting in log.

When I run this:

# update-rc.d zabbix-agent2 defaults 99      
# update-rc.d zabbix-agent2 start 99 2 3 4 5 . stop 5 0 1 6 .
update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults​​ 

Could you give me a hint where to find some log's or what to configure?