Timeout when trying to open Rochetchat

Description

I installed Rocketchat for CentOS following the steps at the following page:
https://docs.rocket.chat/installation/manual-installation/centos/
I opened port 3000 in the firewall

Server Setup Information

  • Version of Rocket.Chat Server: latest
  • Operating System: CentOS 7
  • Deployment Method:
  • Number of Running Instances: 1
  • DB Replicaset Oplog:
  • NodeJS Version: v12.16.1
  • MongoDB Version: v4.0.19
  • Proxy: nginx/apache/varnish
  • Firewalls involved:CSF

Any additional Information

When I want to open http://example.com:3000 it keeps loading until it timesout.