iptables – Cannot access to website after installing cockpit

I have no idea what happened in my system. I have installed cockpit then I realize I cannot access to my website, which is hosted in my server, anymore.

Even when I remove cockpit, which contains NetworkManager, I still cannot access.

There are some info as below. Could anyone give me some advice? Thank you very much.

I disable firewalld and replace with iptables.

~ sudo systemctl status firewalld -l
● firewalld.service
   Loaded: masked (/dev/null; bad)
   Active: inactive (dead)
~ sudo systemctl status iptables -l
● iptables.service - IPv4 firewall with iptables
   Loaded: loaded (/usr/lib/systemd/system/iptables.service; enabled; vendor preset: disabled)
   Active: active (exited) since Mon 2021-02-22 00:31:58 +07; 9s ago
  Process: 9785 ExecStop=/usr/libexec/iptables/iptables.init stop (code=exited, status=0/SUCCESS)
  Process: 11931 ExecStart=/usr/libexec/iptables/iptables.init start (code=exited, status=0/SUCCESS)
 Main PID: 11931 (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/iptables.service

Feb 22 00:31:58 ssdnodes-68686 systemd(1): Starting IPv4 firewall with iptables...
Feb 22 00:31:58 ssdnodes-68686 iptables.init(11931): iptables: Applying firewall rules: (  OK  )
Feb 22 00:31:58 ssdnodes-68686 systemd(1): Started IPv4 firewall with iptables.
~ sudo systemctl status ip6tables -l
● ip6tables.service - IPv6 firewall with ip6tables
   Loaded: loaded (/usr/lib/systemd/system/ip6tables.service; enabled; vendor preset: disabled)
   Active: active (exited) since Mon 2021-02-22 00:32:04 +07; 15s ago
  Process: 9854 ExecStop=/usr/libexec/iptables/ip6tables.init stop (code=exited, status=0/SUCCESS)
  Process: 11962 ExecStart=/usr/libexec/iptables/ip6tables.init start (code=exited, status=0/SUCCESS)
 Main PID: 11962 (code=exited, status=0/SUCCESS)

Feb 22 00:32:04 ssdnodes-68686 systemd(1): Starting IPv6 firewall with ip6tables...
Feb 22 00:32:04 ssdnodes-68686 systemd(1): Started IPv6 firewall with ip6tables.
Feb 22 00:32:04 ssdnodes-68686 ip6tables.init(11962): ip6tables: Applying firewall rules: (  OK  )

When list the units with sudo systemctl list-units command. There are some info of iptables service as bellow.

  ip6tables.service                                         loaded active exited
  iptables-openvpn.service                                  loaded active exited
  iptables.service                                          loaded active exited
  mariadb.service                                           loaded active running
  network.service                                           loaded active exited
  nginx.service                                             loaded active running
  openvpn-server@server.service                             loaded active running
● openvpn@server.service                                    loaded failed failed
  php-fpm.service                                           loaded active running