Connection refused when attempting to connect to a remote host

Symptoms

You may encounter issues connecting to a remote host with an error stating the connection was refused.

Description

This issue is often caused by a firewall, a network-level block, or a proxy service (such as CloudFlare) not proxying the specific port. You can use several tools to troubleshoot the connection and determine where the problem exists. The simplest tool to locate the source of the issue is traceroute.

Workaround

1. Access the server's command line via SSH or "Terminal" in WHM or cPanel.
2. Run a traceroute to the remote host on the desired port.

   traceroute -T -p $port $remote.domain.tld

   Please note that "$port" and "$remote.domain.tld" must be replaced with the remote port number and the remote host's domain name or IP address, respectively.
   Please note that "-T" must be replaced with "-U" when running a traceroute to a UDP port.

If the traceroute doesn't leave the server, the problem is caused by the local firewall. Your system administrator will have to adjust the firewall as needed.

If the traceroute makes it to the destination host, the problem is at the remote end. The remote system administrator will have to make adjustments to the relevant configurations.