The problem is I have migrated to fail2ban 0.10.xx due to which the logpath is not accepting more then log file. So sub section has to be created to accept multiply logs files.
Here is the /etc/fail2ban/jail.d/yunohost-jails.conf
Note: As the maxtry value is 6 when the attacks occur from IP6 I have observed that first IP6 gets ban then then attacks fallback to IP4 which then gets ban. So a particular server attack is ban by 12 attempts which is obvious too, 6 for IP6 and 6 for IP4.