Using PowerShell you test TCP/IP connectivity over port 9000 to your Graylog instance. You use these commands:
$tcp = New-Object System.Net.Sockets.TcpClient
You get "Exception calling "Connect" with "2" argument(s): "N connection could be made because the target maching actively refused it."
You know there is no firewall blocking port 9000. Using nmap you test TCP/IP connectivity over port 9000 to your Graylog instance. You find the port is close and not blocked. You try to use curl http://x.x.x.x:9000. You get this message: "curl: (7) Failed to connect to x.x.x.x port 9000: Connection refused"
What could be wrong?
You have insufficient processor power on the Docker host. On the Docker host, run the "top" command. If you see loads above 2, then you appear to have insufficient processors for deploying Graylog. You need a server with significantly more processors for Graylog to run smoothly.