If your connection coming from a fix IP address you can add it to ignoreip in jail.conf
# "ignoreip" can be an IP address, a CIDR mask or a DNS host. Fail2ban will not
# ban a host which matches an address in this list. Several addresses can be
# defined using space (and/or comma) separator.
ignoreip = 127.0.0.1/8
Furthermore, do you have also SELinux or AppArmor enabled?
First, try to disable it and check if you are banned again.
If problem persists, re-enable SELinux and modify nginx-proxy.conf like this:
[nginx-proxy]
enabled = true
filter = nginx-proxy
logpath = /var/log/nginx/access.log
action = iptables-multiport[name=NoNginxProxy, port="http,https"]
maxretry = 10
bantime = 60
findtime = 120
Increase maxretry to 10, reduce bantime to 60 seconds, reduce findtime to 120 seconds.
This, of course, must be balanced between the grade of security you want and the block that you receiving.