When trying to host your 4D Server and making it accessible to a public network, make sure of the following steps:

1. Obtain your public IP address via https://whatismyipaddress.com/ which 4D Clients will use to connect to your server. The IP address format should be : (E.G. 123.123.123.123:19813).

2. Make sure the following 4D Server ports are open. By default, the ports are:
19812 - SQL Server
19813 - Application Server
19814 - Database Server

Forwarding ports can vary as it is dependent on the router so consulting with a network engineer is advised. Otherwise, to check whether the ports are open, you can use the site below:
https://www.yougetsignal.com/tools/open-ports/