SQL Server listening port not showing in errorlog

Does any one know why the port my SQL Server is listening on would not be recorded in my errorlog? TCP/IP is enabled and default listening port 1433 configured. I have this issue on two servers: - one with a SQL 2008 configured - I can connect remotely to the instance from the management server using SSMS. However, I am unable to connect from the application I am testing connectivity from - the other is a SQL 2016 - I can also connect remotely to this from the management server and from the application I am testing connectivity from. Port 1433 is open on both host machines - netstat -na I expect to see an entry for listening port in my errorlog, would anyone know why it could be missing? thank you