Unable to open Plesk: "ERR_CONNECTION_TIMED_OUT" or it goes on looping endlessly while accessing login page

Symptoms

• Plesk is not accessible with the next error:

  CONFIG_TEXT: This site can’t be reached
  203.0.113.2 took too long to respond.
  ERR_CONNECTION_TIMED_OUT

  or goes on looping endlessly while accessing the login page.

• The ports 8443 or/and 8880 are filtered:

  # nmap 203.0.113.2 -p8443,8880
  
  8443/tcp filtered https-alt
  8880/tcp filtered cddbp-alt

Cause

Ports 8443 or/and 8880 which is used by Plesk user interface are blocked by the firewall.

Resolution

Note: if Plesk is installed on AWS instance, refer to the AWS documentation for instructions on how to open ports 8443 and 8880.

1. Connect to the server via SSH.

2. Allow connections to ports 8443 and 8880:

   • For SystemV-based OSes and SystemD where firewalld is disabled:

     # iptables -A INPUT -p tcp --dport 8443 -j ACCEPT
     # iptables -A INPUT -p tcp --dport 8880 -j ACCEPT

   • For SystemD-based OSes where firewalld is enabled:

     # firewall-cmd --zone=public --permanent --add-port=8443/tcp
     # firewall-cmd --zone=public --permanent --add-port=8880/tcp
     # firewall-cmd --reload

3. Check the next article in order to open other ports nessasary for Plesk working capacity:

   What ports need to be opened for all Plesk Services to work with a firewall?